The Greeks won the Trojan War. According to the most well-known version of the myth, the Greeks used a cunning trick by building a large wooden horse (the famous "Trojan Horse") and leaving it as a supposed offering to the Trojans. The Trojans brought the horse inside their city walls, not knowing it was filled with Greek warriors. At night, these warriors emerged, opened the gates for the Greek army, which had pretended to sail away, and then the Greeks sacked the city of Troy, ending the war.
Although the Greeks won, the war caused great destruction and loss on both sides, with many heroes and kings dying, and the aftermath brought hardship to the Greek victors as well.