Yes during WW2, Finland fought both Germany and the USSR. The Soviets wanted an isthmus from Finland that gave access to Leningrad. The Finns didnt want to give it up so when the Soviets invaded Finland the Finns fought back valiantly. Later during the war without Soviet aggression, Finland finally declared war on a clearly losing Germany.

http://www.history.com/this-day-in-history/finland-declares-war-on-germany

Sorry, we don't allow throughout history questions. These tend to produce threads which are collections of trivia, not the in-depth discussions about a particular topic we're looking for. If you have a specific question about a historical event or period or person, please feel free to re-compose your question and submit it again. Alternatively, questions of this type can be directed to more appropriate subreddits, such as /r/history or /r/askhistory.

If you want to narrow it down though, I might suggest asking specifically about American involvement in the Mexican Revolution, as it is a pretty well known example.