From the Wikipedia entry:
The Four Chaplains were four U. S. Army chaplains who were killed in action when the USAT Dorchester was hit by a torpedo and sank on February 3, 1943. They helped other soldiers board lifeboats and gave up their life jackets when the supply ran out. 230 of the 904 men aboard the ship were rescued
.On 19 December 1944, all four chaplains were posthumously awarded the Purple Heart and the Distinguished Service Cross. The Chaplain's Medal for Heroism was authorized in 1961 and posthumously presented by the President of the United States to the families of the chaplains.
The chaplains were also honored with a stamp,
issued in 1948