Gogo's lie- Detective Riddle

Gogo told a story about how he was awarded a medal for 'bravery during World War 1.' Why is this a lie?

They didn’t know there was going to be a World War 2 at the time, so they wouldn’t have said World War 1 They didn’t know there was going to be a World War 2 at the time, so they wouldn’t have said World War 1