The Greek city-states which did not side with Persia.
The Persians and their Greek allies were united to prosecute the war. Many Greek city-states were united against the Persian and allied forces.
Persian War I, Persian War II, The Peloponnesean War, The Macedonian War, …
Xerxes I.
The Persians would have won if Sparta and Athens had not united to fight the Persian Army
By the Persian king Xerxes.
He was below military age during the Persian War. He fought in the Peloponnesian War.
The Mycenean age was gone 700 years before the Persian War began.
The most important during the 50 years of war which turned the result was the defeat of the Persian navy at Salamis in 480 BCE
The United States and The United Kingdom
The United States Navy patrolled the Persian Gulf during the 1980's and maintained an open sea for fuel tankers traversing the gulf: See Iran-Iraq War (1980-1988).
Yes. The United States achieved its major objective in the Persian Gulf War of 1990-1991: Ending the Iraqi Occupation of Kuwait.
President Reagan during the Iraq-Iran Persian Gulf War; Truman for the Korean War; Eisenhower, Kennedy, Johnson, Nixon, and Ford for Vietnam.