Actually, yes. Christian samurai were used as mercenaries in the Philippines by the Spanish and Portuguese, to fight other Japanese pirates! Piracy was endemic during this time period, and pirate forces often had semi-official sponsors from the southern daimyo, as well as large numbers of ronin and former soldiers. Wakou pirates could be found through as far south as Vietnam and Indonesia, but were most notorious for raiding the Chinese coastline in great numbers. The raids eventually became so bad that much of the coastline was ordered to be abandoned, rather than provide further opportunities for pillaging. It wasn’t until the rise of the Tokugawa that piracy was suppressed in the region.
I vaguely recall having seen over at /r/askhistorians at some point that there were a handful of samurai sent out as ambassadors by some Christian(-friendly) Daimyo to either the Portuguese or Spanish who may have then done something in the new world.
Yes, they fought in the Imjin War, or the Japanese invasion of Korea, which is essentially the medieval Asian version of Napoleonic War. It’s a very interesting war to study which you can read the wiki article to learn a lot more about. They usually held superiority in land due to widespread use of muskets and far more experience in combat compared to Korean or Chinese troops, but held a significant disadvantage in the sea due to the lack of firepower. They also had some blunders in the land, such as Battle of Hangju, and were facing fairly large guerrilla forces that they were not accustomed to fighting against. I’ll write a basic summary of the war below though.
Toyotomi Hideyoshi, one of the retainers of Oda Nobunaga, rose to power after Nobunaga’s death. He essentially united the clans under the Hideyoshi banner (though it wasn’t perfect as rival clans such as it had plenty of dissenters such as the Tokugawa clan who were also loyal to the Oda clan) and decided to expand his rule abroad. His ultimate goal was to use his experienced army overseas to China, making him the one and only leader of East Asia. To do so, he demanded passage through Korea, which the Joseon Dynasty refused for various reasons (they were vassal of Ming Dynasty (China), thought Hideyoshi was a joke, etc.).
In response, Hideyoshi invaded Korea, prompting the 6 year war. At first, the well-experienced Japanese army with muskets were able to beat the fairly inexperienced southern Korean forces quickly, capturing the capital, Seoul, rapidly. However, there was a particular flaw in the strategy. In Sengoku Jidai, it was considered the leader’s duty to stay within his castle, the capital, and face the enemy head on no matter how hopeless the situation was. Capturing the capital was thus the end of the war. But, Korea didn’t have that kind of mindset. So when the King Seonjo left the capital safely, the Japanese were confused. In addition, because they bypassed a lot of the regions in the South to quickly reach Seoul, guerrilla forces started fighting against the Japanese on their own, disrupting the supply chain.
Another problem was that the Japanese were fairly inexperienced in naval battles due to their focus on land battles during the Sengoku Jidai. In addition, a Korean admiral by the name of Yi Sun-sin was quite a bit of military genius. He destroyed Japanese fleet time after time, never losing a single battle and never losing a single ship to the point that Hideyoshi ordered to avoid fighting Yi on sea at all costs. This had profound effect on the supply of Japanese Army as they had to transport everything by land, which took way too long for their armies now marching up north. In addition, at this time, the Ming dynasty sent their army and navy down to assist their vassal despite having their own trouble against the Later Jing (Qing). At the end, Hideyoshi died while the war was on the stalemate, prompting the pro-Hideyoshi clans that were the main forces in Korea in a rush to head back to protect the next Toyotomi clan head from the anti-Toyotomi clans such as the Tokugawa. The war ended in Japanese tactical defeat, though Korea and China both suffered a lot from the war.
Ahh you saw the samurais at the Sphinx yesterday on Reddit and wondered this didn’t you? Cuz I did
It depends how you define Samurai.. i assume you mean the traditional katana-wielding warlord/noble class individuals from early modern Japan
In which case I am not aware of the Samurai fighting as a cohesive group overseas in any kind of military campaign other than in Korea, the Japanese state was a very insular nation, But there are many accounts of individual Samurai leaving Japan and effectively becoming mercenaries, Yamada Nagamasa is a well known example who travelled from Japan to Thailand/Burma and was involved in the various conflicts going on in that region around the 16th century.
There was also the Wokou-pirate phenomenom in the 13th century where bad famines in Japan and Korea lead to huge numbers of Samurai turning to piracy for money by raiding along the Chinese/Korean/Japanese coasts, once the Mongol’s took Korea this piracy became one of the reasons for the Mongol attempt at invading Japan.
In 1586 the Spanish also attempted to invade China by mustering forces in the Phillipines and Taiwan (Spain had gained access to the Portuguese colony on Taiwan during the personal union period with Portugal starting 1580), this planned invasion force was intended to feature Samurai mercenaries.