John was born in Luzon, Philippines, on the 8th of February, 1904. His family moved to Minnesota and he had wanted to attend West Point but his poor eye sight kept him from attending and he ended up studying engineering at Princeton University. John was a member of the Reserve Officer Training Corps and when he graduated from Princeton in 1926, he received a varsity letter in pistol and his commission in the Army Reserve.

During World War 2, John spent much of his time at Fort Sill, Oklahoma, training artillery troops since he was considered to be a great teacher. He eventually would be deployed to Germany in command of an artillery battery and after the War, John was able to get out of more classroom duty in exchange for deploying to Korea. He had wanted more combat assignments and when he arrived in Korea, he was immediately put to work and it was his actions over his first 12 days in country that would earn him the Medal of Honor. The citation reads:

Lt. Col. Page, a member of X Corps Artillery, distinguished himself by conspicuous gallantry and intrepidity in action above and beyond the call of duty in a series of exploits. On 29 November, Lt. Col. Page left X Corps Headquarters at Hamhung with the mission of establishing traffic control on the main supply route to 1st Marine Division positions and those of some Army elements on the Chosin Reservoir plateau. Having completed his mission Lt. Col. Page was free to return to the safety of Hamhung but chose to remain on the plateau to aid an isolated signal station, thus being cut off with elements of the marine division. After rescuing his jeep driver by breaking up an ambush near a destroyed bridge Lt. Col. Page reached the lines of a surrounded marine garrison at Koto-ri. He then voluntarily developed and trained a reserve force of assorted army troops trapped with the marines. By exemplary leadership and tireless devotion he made an effective tactical unit available. In order that casualties might be evacuated, an airstrip was improvised on frozen ground partly outside of the Koto-ri defense perimeter which was continually under enemy attack. During 2 such attacks, Lt. Col. Page exposed himself on the airstrip to direct fire on the enemy, and twice mounted the rear deck of a tank, manning the machine gun on the turret to drive the enemy back into a no man's land. On 3 December while being flown low over enemy lines in a light observation plane, Lt. Col. Page dropped hand grenades on Chinese positions and sprayed foxholes with automatic fire from his carbine. After 10 days of constant fighting the marine and army units in the vicinity of the Chosin Reservoir had succeeded in gathering at the edge of the plateau and Lt. Col. Page was flown to Hamhung to arrange for artillery support of the beleaguered troops attempting to break out. Again Lt. Col. Page refused an opportunity to remain in safety and returned to give every assistance to his comrades. As the column slowly moved south Lt. Col. Page joined the rear guard. When it neared the entrance to a narrow pass it came under frequent attacks on both flanks. Mounting an abandoned tank Lt. Col. Page manned the machine gun, braved heavy return fire, and covered the passing vehicles until the danger diminished. Later when another attack threatened his section of the convoy, then in the middle of the pass, Lt. Col. Page took a machine gun to the hillside and delivered effective counterfire, remaining exposed while men and vehicles passed through the ambuscade. On the night of 10 December the convoy reached the bottom of the pass but was halted by a strong enemy force at the front and on both flanks. Deadly small-arms fire poured into the column. Realizing the danger to the column as it lay motionless, Lt. Col. Page fought his way to the head of the column and plunged forward into the heart of the hostile position. His intrepid action so surprised the enemy that their ranks became disordered and suffered heavy casualties. Heedless of his safety, as he had been throughout the preceding 10 days, Lt. Col. Page remained forward, fiercely engaging the enemy single-handed until mortally wounded. By his valiant and aggressive spirit Lt. Col. Page enabled friendly forces to stand off the enemy. His outstanding courage, unswerving devotion to duty, and supreme self-sacrifice reflect great credit upon Lt. Col. Page and are in the highest tradition of the military service.

Originally, these actions earned him the Navy Cross but it wasn't until the 25th of April, 1957, that the Navy Cross would be upgraded to the Medal of Honor with a waiver from Congress being needed due to the length of time that had passed. A military sealift command ship was named in his honor, as well as Camp Page at the DMZ until it was closed in 2005. John had been married to Margaret Wood and had two children, Margaret and Dennis. John Upshur Dennis Page was 46 years old when he died and he is buried in Arlington National Cemetery: Section 4, Lot 2743-A-B.