Seipan

On a June much like this one..

During world war II, Saito and his men were doing all they could to hold the mountains of Saipan from the Americans, but Emperor Hirohito sent out an imperial order commanding the Japanese civilians of Saipan to commit suicide, promising that any who followed the order would be given an equal spiritual status in the afterlife as the soldiers who died fighting. 

As the fighting on Saipan continued, Japanese citizens headed to the Northern tip of the island, chose two specific areas, known today as Banzai Cliff and Suicide Cliff, and jumped to their deaths. The majority of the suicides happened in the last four days of fighting, between July 8th and July 12th. 

By the end of the fighting, 24,000 Japanese soldiers were dead, 5,000 by their own hands, including General Saito, who was found dead in a cave alongside Vice-Admiral Chuichi Nagumo, the naval commander who lead the Japanese carriers that attacked Pearl harbor. Even worse, 22,000 of the 25,000 Japanese civilians were dead as well, almost all of them had taken their own lives.

http://www.the13thfloor.tv/