Simplify the following text for a Grade 6 native English-speaking person.
Original: This makes the battle one of the most catastrophic defeats in the history of Ancient Rome , and one of the bloodiest battles in all of human history ( in terms of the number of lives lost within a single day ) .
Simplified: This makes the Battle of Cannae one of the worst defeats in the history of Ancient Rome . It is also one of the bloodiest battles in all of human history in terms of the number of lives lost within a single day .