The answer would be A. American Revolution.
In the Six-Day War (1967) the countries were: Israel, Egypt, Syria, Jordan, and Iraq.
In the War of Attrition (1967-1970) countries were: Israel, Egypt, Soviet Union, PLO (Palestine Liberation Organization), and Jordan.
In the Yom Kippur War (1973) countries were: Israel, Egypt, Syria, Iraq, Jordan, Algeria, Morocco, Saudi Arabia, and Cuba.
So it would be Israel and Egypt. Sorry for that. I forgot it said 'what TWO'.
The number of samurai began to decrease because there was no need for them anymore due to the lasting peace.
These victories greatly boosted American morale, because it showed to the Americans that they could beat the great British army (although those two victories weren't exactly large victories, a technically "cheap" move made by Washington).