They were five brothers from America who enlisted in the US Navy back in January 1942 to avenge a friends death during the battle in Pearl Harbour.
On their enlistment they stipulated that they wanted to serve together upon the same ship and consequently, they were assigned to the light cruiser USS Juneau.
Unfortunately, during the Battle of Guadacanal on 13th November 1942, 600 crew members were killed including the five Sullivan brothers.
The fighting Sullivan Brothers became national heroes, and as a result of their deaths, the US War Department introduced the Sole Survivor Policy. This is a set of regulations used in the US Military created to protect members of the same family from conscription or combat duty if they have previously lost a family member during combat duty.