For the USA the obvious candidates are the Revolutionary War, and the Civil War.
For Australia, Anzac Day and Gallipoli.
For Japan one such event or period seems to be the Meiji Restoration.
From recent anime like Gun+Sword (which I haven't seen) to Rurouni Kenshin to some much older titles it seems to be a period that constantly draws attention from the artists of each generation. I'm less familiar with live action interpretations but I must note in passing "The Last Samurai".
One older, and in my opinion classic, treatment of the period is found in the 1985 Toei film "Dagger of Kamui" based on novels by Tetsu Yano.
I've long been a fan of the film and sat down to rewatch it this evening. This is less of a review than a collection of impressions and reflections.
Like some other treatments (possibly including the Ninja Scroll OAV) it revolves around a shinobi/ninja Jiro and a "secret history" of the time.
The hero Jiro and his trials feel like a lens through which the viewer can interpret the Japanese experience of the period. For example, the opening of Japan by Commodore Perry is in some sense represented by Jiro's trip to America during the film.
For those expecting the completely over the top theatrics and special attacks of later ninja anime you will be disapppointed. Such things are in the movie but refreshingly understated, I especially appreciate the lack of long winded explanations.
There are elements in the plot (especially the secret history of Japan and a certain pirate) that seriously stretch the suspension of disbelief but these are carried off with such style that the film just rolls over you and you enjoy it anyway. Of course it might help to be a style junkie. :)
Villains, ninjas, lost siblings, cowboys and indians, pirate treasure, war, a romantic interest that is (strongly) hinted at but not resolved in the film, whats not to like?