Answer
Before Lysimachus became king, he was an officer in the Macedonian army. He was a close friend and ally of Alexander the Great, and he served as his bodyguard during the Battle of Gaugamela. After Alexander's death, Lysimachus became one of the Diadochi, or the generals who fought to control the Macedonian Empire. He eventually became the ruler of Thrace and Macedonia, and he founded the city of Lysimachia.