Jack Davenport was born on September 7, 1931, in Kansas City, Missouri. He enlisted in the U.S. Marine Corps on July 25, 1950, and completed basic training at Marine Corps Recruit Depot San Diego, California, in October 1950. PFC Davenport was then assigned to the Training and Replacement Command at Camp Pendleton, California, from October to December 1950. He served with Company G, 3rd Battalion, 5th Marine Regiment of the 1st Marine Division in South Korea from December 1950 until he was Killed in Action on September 21, 1951. Corporal Davenport was buried at the Mount Moriah Cemetery in Hickman Mills, Missouri, and he was posthumously awarded the Medal of Honor for his heroism the day he was killed.

His Medal of Honor Citation reads:

For conspicuous gallantry and intrepidity at the risk of his life above and beyond the call of duty while serving as a Squad Leader in Company G, Third Battalion, Fifth Marines, First Marine Division (Reinforced), in action against enemy aggressor forces in the victim of Songnae-Dong, Korea, early on the morning of 21 September 1951. White expertly directing the defense of his position during a probing attack by hostile forces attempting to infiltrate the area, Corporal Davenport, acting quickly when an enemy grenade fell into the foxhole which he was occupying with another Marine, skillfully located the deadly projectile in the dark and, undeterred by the personal risk involved, heroically thew himself over the live missile, thereby saving his companion from serious injury or possible death. His cool and resourceful leadership were contributing factors in the successful repulse of the enemy attack and his superb courage and admirable spirt of self-sacrifice in the face of almost certain death enhance and sustain the highest traditions of the United States Naval Service. Corporal Davenport gallantly gave his life for his country.