‘Age of Samurai: Battle for Japan’ Full Review (Pt. 2)

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For a review of episodes 1-3, click here.

Welcome back! We are continuing to look into the Netflix docuseries, Age of Samurai: Battle for Japan, which was released in February 2021. In light of recent events, I have decided to release an episode-by-episode review of the series. As stated in the first part of this review, this docuseries has been nominated for a RealScreen Award this year, which was supposed to take place on January 25-28, 2022, however, due to rising Omicron Covid-19 cases in the United States, the 12th Annual RealScreen Summit has been postponed until June 6-9, 2022. The docuseries did not win the category it was nominated for.(1)

Just a recap, this review is only going to focus on the historical problems in Age of Samurai. For a list of people I recommend to check out when it comes to identifying problems regarding the smaller details of the reenactments (i.e., armor types, weapons, settings, etc.), please visit the first part of this two part review and go to the end of the article.

This review is going to focus on episodes 4-6, the last three episodes in the six-episode docuseries. See the top of the article for a link to part one of this two-part review.

Episode 4: Complete Control

Date Masamune from Age of Samurai: Battle for Japan

The fourth episode is a bit odd. It begins with Shizugatake and goes through how Hideyoshi gained control of Japan, but that is not the main focus of this episode. The main topic of the episode is the northern daimyō, Date Masamune. The episode covers the years 1583-1590, but most of the episode is focused on Masamune rather than Hideyoshi. The episode ends with a setup to talk about the Korean Campaigns in the next episode. This episode is by far the worst when it comes to information, mainly regarding the edicts put in place by Hideyoshi.

Shibata Katsuie and Shizugatake

As promised, I wanted to talk about how we got to Shizugatake. While this is a callback to episode 3, Shizugatake does not get a lot of time in this episode (a total of about seven minutes), but there were only a couple of problems here. They first, fail to mention the importance of Shibata Katsuie. Not only was he a loyal retainer of the Oda, but he was also Oda Nobunaga’s cousin. Even more still, Katsiue was married to Oichi in the winter of 1582 to seal his alliance with Oda Nobutaka, who he sided with during the Oda succession dispute.(2) While the events leading up to Shizugatake were pretty spot on, they failed to mention that Shizugatake started off as a night attack. The battle began with an attack in the early morning hours, using pine torches to light their way, but the reenactment made it during the day.(3) This was the reverse of what happened to Okehazama in episode one, yet I do not understand why they did not make it a night attack. It is obvious that they have drummed up a lot of the events in the reenactments, to make them more dramatic, however, they completely missed a chance on this one.

Date Masamune and Smallpox

Going back to the opening of this episode, we are treated to a man who is gauging out his own right eye…did I mention that the reenactments are pretty graphic? They do explain who he is after they talk about Shizugatake, Ieyasu’s surrender to Hideyoshi and him gaining the title of Prime Minister, so it seems like an odd and jarring way to open an episode. To those who do know our Sengoku history, we know right away that it is Date Masamune. Looking back to the trailer last year, I was surprised to see that he got a mention, and I do admit that Masamune’s placement in the docuseries is weird to me. They could have spent more time on Hideyoshi’s campaigns in Shikoku, Kyūshū, and Odawara, but instead, the focus shifts to Masamune. Please don’t get me wrong, I love Date Masamune. He is an interesting figure in Japanese history, and he was my introduction to studying the Sengoku Jidai, but hear me out on this. The trailer, for the most part, acts like this docuseries is going to focus on the Three Unifiers of Japan: Oda Nobunaga, Toyotomi Hideyoshi and Tokugawa Ieyasu. Even the series starts out this way as we have followed the campaigns of Oda Nobunaga and the beginning of Toyotomi Hideyoshi’s rise to power, but now it has been diverted to focus on Date Masamune. Honestly, Masamune should have gotten his own documentary rather than trying to shoehorn him in while talking about the Three Unifiers of Japan. Since they have decided to do this though, we will be talking about him.

To begin, Date Masamune (September 5, 1567-June 27, 1636) was a powerful daimyō who controlled many of the northern domains and would later side with Tokugawa Ieyasu during the Sekigahara Campaign. Though he would never make it to Sekigahara proper, he would be able to stop the Uesugi from attacking the Tokugawa and participating in the battle for the Western Army. The documentary begins with his bought with smallpox, which ended up infecting his right eye at some point, to which it was removed. While we see him as an adult removing the eye by himself, this would have possibly happened while he was younger and according to some records, he did not remove it himself. One popular story states that he had his trusted retainer, Katakura Kojūrō remove the eye for him.(4) They were right about his mother wanting to poison him and in retaliation killed his own brother, though.(5)

Ōuchi Sadatsuna and the Slaughter

I actually had to go back and watch this episode again, because I had a hard time finding anything on the siege that is talked about in this episode. It is pertaining to the siege and then slaughter at Odemori Castle after Date Masamune learned of Ōuchi Sadatsuna’s betrayal to the Ashina clan. The problem is the one source I did find on this states that the castle’s name is Odamori. Even so, Google searching both spellings bring up nothing about the castle or siege on its own. Even worse is that only one source even mentions this siege when searching for Date Masamune. My other go-to sources have nothing on this either, which makes it complicated to learn anything more than what has been presented to us in this documentary. Perhaps when I finally learn to read Japanese, I will be able to read the biographies on him and learn more about this, but for now, I will have to take the word of the historians in Age of Samurai and this one article I have managed to find.(6)

Toyotomi Edicts

This sent me on a wild goose chase, mainly because the information in the episode is extremely wrong. The historians bring up two different edicts that were put in place by Hideyoshi: the “Sword Hunt” and the “Peace Edict”. Let’s start with the famed “Sword Hunt” first.

In almost any book you can find on the history of Japan, this era of Japanese history is never missed. In 1588, Hideyoshi issued the “Sword Hunt”, which meant that swords owned by farmers would be rounded up, disarming the Japanese peasant population. That’s right, the “Sword Hunt” specifically mentioned farmers.(7) Lower-ranking samurai and those of the warrior classes were allowed to keep their weapons and there were some exceptions as well, such as hunters and districts that still dealt with pirates.(8) The episode made it sound like it applied to all peasants, but in reality, it specifically targeted farmers. This was most likely in response to the violent uprising by the farmers in Higo in 1587, but this also, along with the Separation Edict, would keep farmers tending to their fields, rather than spurring revolts.(9) The episode also paints this out to have been a violent endeavor, but records show that there were, surprisingly, no resistance to it.(10) The reason? It was stated in the edict itself that weapons that were handed over to the katana-gari bugyō (sword-collecting magistrates) would be melted down to be used in the construction of the Great Buddha: “This is an act by which the farmers will be saved from this life, needless to say, and in the life to come.”(11) By appealing to their religious beliefs, this ensured a peaceful transfer, for the edict also stated that those who did not comply would be “brought to judgement”.(12) Again, the reenactment drummed up drama to keep viewers entertained rather than portraying the truth. Then there is the “Peace Edict”.

I have searched high and low for information on the “Peace Edict”, which according to the documentary, was the edict that made it illegal to go to war independently. When it comes to Hideyoshi, the great political things that he is known for are the “Sword Hunt”, the “Separation Edict” and land surveys. Nowhere have I found anything about a “Peace Edict”, expect for one place, but it is not what the historians in the documentary say it is. The “Peace Edict” ordered all daimyō to lay down their arms and submit to the Toyotomi.(13) This had nothing to do with ability to declare war, but rather a last-ditch effort to end the wars in Japan without any more bloodshed. Of course, there were daimyō who refused this, as we see with the Hōjō, but it was not a decree that gave Hideyoshi control of warfare.

Masamune’s Late Arrival to Odawara

The last bone I have to pick with this episode is the depiction of Masamune’s late arrival and surrender to Hideyoshi in 1590. The episode makes it look like Masamune’s submission to Hideyoshi came after the Odawara Campaign had come to an end. Historically, however, Masamune surrendered before the Hōjō.(14) While it is true that he was one of the last to acknowledge Hideyoshi as the supreme leader, Masamune came to the Toyotomi camp before the Siege of Odawara ended, not after.

Episode 5: Catastrophe

Toyotomi Hideyoshi in Age of Samurai: Battle for Japan

This episode covers the Korean Campaigns and the decline of Toyotomi Hideyoshi, leading up to the events of Sekigahara, which is covered in the final episode. I had to do some research on this topic, for I knew very little about the Imjin War (1592-1598) and I wanted to make sure I had some idea of what happened before diving into this part of the review.

Konishi Yukinaga

I have had a lot of people mention Konishi Yukinaga (1558-November 6, 1600) to me in YouTube and Facebook comments, and he is a fascinating figure I would love to cover in a more in-depth article, and he does get an appearance in this docuseries. He is not a well-known figure, but he was a Christian daimyō who served under Hideyoshi and led the first forces into Korea.(15) They made him out to be just a negotiator for the Korean Campaign, when he actually did so much more. I did notice something while watching this episode and I chalk it up to an editing problem. When Isaac Meyer was talking about Yukinaga, he referred to him as his Christian name, Augustine, but it was only once. The episode never mentioned that Yukinaga was Christian, so unless the viewer knew that Yukinaga’s Christian name was Augustine this would be very confusing.

The Problem with the Korean War

While I did like that the Imjin War was covered in the documentary, especially since that it is not well covered in English sources, I felt like they glossed over a lot. The episode focused mainly on the warfare that took place on land, and while that is impressive, some of the most impressive parts of the Imjin War took place on the water. There was not a single mention of the famous turtle ships nor of Admiral Yi (April 28, 1545-Deceber 16, 1598).(16) Again, I know it is only a fifty-minute episode, but this is too deep of a topic to do in just one episode. Instead of focusing on the war in Korea exclusively, they decide to also focus on the problems with Hideyoshi back in Japan.

The Problem with Hidetsugu and Masamune

Back in Japan, Hideyoshi is struggling with the idea that he does not have an heir to take over if something were to happen to him. As stated in the documentary, for a while, the heir to the Toyotomi was Hideyoshi’s nephew, Hidetsugu (1568-July 15, 1595). While they covered this situation well, problems arose when they brought up Date Masamune again. According to the documentary, Masamune extremely close to Hidetsugu and Hideyoshi summoned Masamune to find out the extent of their relationship. Once Hideyoshi was satisfied that Masamune was not part of Hidetsugu’s plan to overthrow Hideyoshi, he was sent to Korea to prove his loyalty. This is not entirely true.

Date Masamune was in Korea as early as 1593 and the incident with Hidetsugu happened in 1595, meaning that being sent to Korea to prove his loyalty was redundant.(17) This does not mean that he did not have problems when trouble arose with Hidetsugu. Masamune’s uncle, Mogami Yoshiaki, had a fifteen-year-old daughter that was sent to Kyōto to be a concubine to Hidetsugu. Though she had not met her husband to-be, Hideyoshi did not spare her and was sentenced to death along with other the other members of Hidetsugu’s family.(18) This, topped with Masamune’s relationship with Hidetsugu, brought the clan under speculation, but the matter was later dropped.

Episode 6: Birth of a Dynasty

An aged Tokugawa Ieyasu in Age of Samurai: Battle for Japan

The last episode of the docuseries focuses on the events leading up to Sekigahara, the battle itself and the end of the Toyotomi at Ōsaka.

The Reasons behind the Last War

I am not sure if this is another editing flaw or if events got confused, but the reasons behind the declaration of war, which would lead to Sekigahara, are not as clear cut as the docuseries makes it out to be. While the regents did disagree with some of the things Ieyasu did, there was not much they could do but voice their displeasure. What brought Japan back into war was the letter that Ishida Mitsunari sent to Ieyasu with a list of charges against him, basically calling him a usurper.(19) They also failed to mention the assassination attempt on Ieyasu’s life, which was set up by Mitsunari. In retaliation, many generals who were loyal to Ieyasu tried to assassinate Mitsunari while he was in Ōsaka, but he managed to escape.(20) There is also the issues of Ieyasu becoming suspicious of the Uesugi who were building up their newly acquired domain and the death of Hosokawa Gracia caused problems for Mitsunari. While there was a lot going on in the year and a half before the Battle of Sekigahara, it was Mitsunari’s letter to Ieyasu that put the country down the path of war once again.

The Sekigahara Campaign

We have talked a lot about Sekigahara on this website, and we have covered the other battles (more like sieges) in other articles, so I will not go into much, but it does feel they rushed through a lot. They covered the Siege of Fushimi Castle, but not the attack at Akasaka which took place the night before the main event. I understand why they left out the others, but to leave out a battle that took place right before the Battle of Sekigahara seems odd to me.

Much of the battle details were left out too, only focusing on the betrayal of Kobayakawa Hideaki and not much on how his betrayal led to the death of Ōtani Yoshitsugu or any mention of Shima Sakon or the famous first charge by Ii Naomasa. Again, much time was wasted talking about how gruesome the battle was rather than about battle tactics or any of the major events that took place in the six-hour battle.

The Ōsaka Campaign

Unfortunately, this last part of the Sengoku Jidai was completely glossed over by the docuseries. They spent the time setting the Siege of Ōsaka by talking about Hideyori and his mother, Lady ChaCha, but for some reason, they did not dive into any of the conflict that happened at Ōsaka in the winter of 1614 and in the summer of 1615. The only time the hostilities are mentioned, is when we are treated to yet another seppuku scene involving Hideyori and Lady ChaCha. No mention of the peace treaty that took place in the winter and then was broken. No mention of Sanada Yukimura’s last charge into battle, getting so close to Ieyasu that he was preparing for seppuku himself.(21) There were a lot of interesting things that happened in this campaign, but it was completely overlooked.

The Relationship between Ieyasu and Masamune

I have not been able to find anything on this relationship that the docuseries said existed between Tokugawa Ieyasu and Date Masamune. Perhaps this is something that is only mentioned in Japanese history books, but as for anything in English, I have not been able to find anything to confirm nor deny their claims in the docuseries. I will update this if I do find any more information on this subject.

The Docuseries Overall

The problems with the docuseries extend beyond the historical problems and the reenactments. First, this is not a docuseries that can be watched by all. This is rated TV-MA for a good reason. The reenactments are extremely graphic and then there are the sex scenes. By only appealing to a mature audience, it limits who can watch this documentary.

I cannot believe I am saying this, but there are way too many historians crammed into this docuseries. There are over twenty historians spread throughout these six episodes and from the way it is edited, it sounds like they are constantly talking over one another. Due to editing, they also repeat themselves and sometimes contradict one another. It also made it difficult to keep track of which one was talking. They would have been better off picking a handful of historians to talk throughout the docuseries and left it at that.

The docuseries glossed over a lot. Again, I understand that there is only so much information that can be put in a documentary, however, so many important and impressive things were left out in favor of longer discussions on things that really did not need to be discussed. For example, the horrors of war. These historians love the word, massacre; so much so you can turn it into a drinking game. Having the historians describe what war was like just felt redundant since we are treated to extremely gruesome reenactments. So much time was spent on this, which could have been spent talking about other campaigns or even more of the political dynamics of the era, but we are stuck with people going on about how everything was brutal hand-to-hand combat.

This was a docuseries that should have been a drama series, which is disappointing. This was a wasted opportunity to talk about things that are not as known in the Western world about the Sengoku Jidai. Unfortunately, we got the same usual information or much of the information was glossed over in favor of others. The addition of Date Masamune, while interesting, disrupted the flow of the docuseries, which obviously focused on the Three Unifiers of Japan. So, the question is, what should you watch instead?

This list is of YouTube videos, podcasts and even books that do a better justice to this era than Age of Samurai: Battle for Japan:

  • The Shogunate YouTube channel. This channel has been around since 2019 and has videos about samurai history, starting as far back as the Gempei War (1181-1185). These are well researched videos, and he even has a video about the sources he uses when it comes to his videos.
  • Extra Credits YouTube channel. This channel has a couple of YouTube series that would be great introductions to the Sengoku Jidai and the Imjin War. They have a six-part series on the Sengoku Jidai and another five-part series on Admiral Yi, the famed Korean commander during the Imjin War.
  • History of Japan Podcast. This podcast has been around since 2013 and it is hosted by Isaac Meyer. With over 400 episodes available and on various topics in Japanese history, this podcast is great for anyone wanting to dive into Japanese history and culture.
  • Sengoku Jidai: Nobunaga, Hideyoshi and Ieyasu: Three Unifiers of Japan by Danny Chaplin. This self-published book is well researched and covers every aspect of this era of Japanese history. It is a tome of a book, but it covers this everything about the Sengoku Jidai: from the battles to politics and even religion.

Age of Samurai: Battle for Japan was a disappointment to many of us who were looking forward to a modern documentary on this era of Japanese history. Instead, we are treated to a drama series that is trying to be a documentary. I did not want to dislike this; however, I cannot recommend this to anyone. Please, if you are wanting to learn more about the Sengoku Jidai, check out the recommendations above and the “Further Information” page. Just avoid this like the plague.


  1. “RealScreen Awards 2022 Winners and Nominees”, https://awards.realscreen.com/Winners/Winner/2022, last visited 6/14/2022
  2. Turnbull, Stephen. Toyotomi Hideyoshi (2010), pp. 29-30
  3. Turnbull, Stephen. Toyotomi Hideoyshi (2010), pp. 32-33
  4. “Date Masamune”, Wikipedia.com. https://en.wikipedia.org/wiki/Date_Masamune, last visited 1/25/2022
  5. “Date Masamune”, SamuraiWorld.com. https://samurai-world.com/date-masamune/, last visited 1/25/2022
  6. “Date Masamune”, Japanese Wiki Corpus. https://www.japanese-wiki-corpus.org/person/Masamune%20DATE.html, last visited 1/25/2022
  7. Sansom, George. A History of Japan 1334-1615 (1961), p. 332
  8. Chaplin, Danny. Sengoku Jidai: Nobunaga, Hideyoshi, and Ieyasu: Three Unifiers of Japan (2018), pp. 373-374
  9. Sansom, George. A History of Japan 1334-1615 (1961), p. 331
  10. Berry, Mary Elizabeth. Hideyoshi (1982), p. 105
  11. Berry, Mary Elizabeth. Hideyoshi (1982), p. 102: direct quote from a translation of the edict.
  12. Berry, Mary Elizabeth. Hideyoshi (1982), p. 102: direct quote from a translation of the edict.
  13. “Chapter 3: Premodern Japan-The Azuchi-Momoyama and Edo Periods”, PDF. http://www.sdh-fact.com/CL02_2/Chapter%203%20Section%201,%202.pdf, last accessed 1/25/2022, information found on p. 10 of document.
  14. “Date Masamune”, Japanese Wiki Corpus. https://www.japanese-wiki-corpus.org/person/Masamune%20DATE.html, last visited 1/25/2022
  15. “Konishi Yukinaga”, Wikipedia.com. https://en.wikipedia.org/wiki/Konishi_Yukinaga, last visited 1/25/2022
  16. “Yi Sun-sin”, Wikipedia.com. https://en.wikipedia.org/wiki/Yi_Sun-sin, last visited 1/25/2022
  17. “Date Masamune”, Japanese Wiki Corpus. https://www.japanese-wiki-corpus.org/person/Masamune%20DATE.html, last visited 1/25/2022
  18. “Mogami Yoshiaki”, Wikipedia.com. https://en.wikipedia.org/wiki/Mogami_Yoshiaki, last visited 1/25/2022
  19. Glenn, Chris. The Battle of Sekigahara: The Greatest, Bloodiest, Most Decisive Samurai Battle Ever (2021), p. 33
  20. Glenn, Chris. The Battle of Sekigahara: The Greatest, Bloodiest, Most Decisive Samurai Battle Ever (2021), pp. 20-21
  21. Yoda, Hiroko & Matt Alt. Ninja Attack! True Tales of Assassins, Samurai, and Outlaws (2012), p. 131