Famous battle or really long race in greek mythology?

According to Greek mythology, the first marathon race took place in ancient Greece when a Greek messenger named Pheidippides ran from the town of Marathon to Athens to deliver news of a Greek victory over the invading Persian army in 490 BC. It is said that Pheidippides reached Athens and uttered the words "We have won" before collapsing and dying of exhaustion. In commemoration of this event, the modern marathon race of 26.2 miles (42.2 kilometers) was established.