Simplify the following text for a Grade 7 native English-speaking person.
Original: The Gaza flotilla raid also known as the flotilla incident of 31 May 2010 , was a military operation by Israel against six ships of the `` Gaza Freedom Flotilla '' on May 31 , 2010 in international waters of the Mediterranean Sea .
Simplified: The Gaza flotilla raid is an event that occurred on 31 May 2010 .