Japanese Idiom ひとはたあげる raising a flag

I had an interesting activity in my class. Each student chose one country's idiom, and literally translated it to English. After that, students guessed what the idiom meant from literal translation. It was a good opportunity to think about Japanese idioms and thier origin.

For example,

一旗あげる (ひとはた　あげるhitohata ageru)

literal translation: raising a flag

Raising a flag? Is Big sale going to be held? Is it for celebrating national holiday?

The meaning is to start your own business. And the reason why it means that is because, in the past, a Samurai would go to the battlefield with his own flag to have his achievement stand out. If they captured opponent's castle, they raised their flags to show victory. The idiom's 'flag' comes from the flag, and the military achievement was changed to mean business achievement.

※According to the website, the definition of "hitohata ageru" is "to make a name for oneself, to achieve success" (FYI) .