What was the cartoon with battleship flying through space?

You're likely thinking of "The Space Battleship Yamato" (also known as "Star Blazers" in the United States).

This Japanese anime series, originally aired in 1974, follows the story of the crew of the titular battleship Yamato as they embark on a perilous journey to a distant planet to seek a cure for Earth's impending destruction from a hostile alien force. The Yamato is a classic, powerful battleship adapted for space travel, hence the flying battleship element you remember.

It's a classic anime with a strong focus on space battles, heroic characters, and themes of hope and survival.