Greeks warred against Troy because Paris took Helen, the King of Sparta's wife. Story's say they got in to the heavily defended city through a giant horse full of soldiers and Achilles was a great warrior in the war. The Greeks soon after won the war.
Sparta wanted Messiaen's fertile land (theorized by scholars). They fought battles almost every year. The Spartans won. and got the land for their gain.
King Darius l wanted more land and to expand and fought Sparta and Athens under the command of Datis and Artaphernes in the battle of Marathon and lost.
King Xerxes wanted to avenge his fathers defeat by Greece and started the second Persian war. After having much success the Spartans trapped the Persian army on land and defeated them. And the Athenian fleet led by Themistocles trapped the Persian fleet and won the war.
Tension between Athens and Sparta rose until war broke out after years of fighting Athens was left bankrupt and exhausted and couldn't fight any longer. and Sparta won. This was documented by the Athenian historian Thucydides.
Alexander Moves his army to Persia and Egypt and takes control within three years. In the siege of Giza Alexander the Great launched is first large scale invasion. Alexander the Greats expansion gave England lots of land making them a big part of history in the current era