This was the first time that a Spartan army lost a land battle at full strength .
Sparta entered its long - term decline after a severe military defeat to Epaminondas of Thebes at the Battle of Leuctra .
This was the first time that a Sparta army lost a land battle at full strength .
Sparta entered its long - term decline after a severe military defeat to Epaminondas of Thebes at the Battle of Leuctra .