John Upshur Dennis Page, attended Princeton University, and received a degree in engineering and an ROTC commission when he graduated in 1926. During World War II he commanded an artillery battalion in Europe. He slowly rose through the ranks and, in 1950, he received an order to attend the Command and General Staff College at Fort Leavenworth. The war in Korea broke out at almost the same time. Instead of spending part of the war in classroom studies, he requested, and received, a combat assignment to Korea.

During the American forces withdrawal from the North Korean/Chinese border in 1950, LTC Page was attached to X Corps headquarters. While on detached service from headquarters he became involved in the fighting around the Chosin Reservoir where, as his Medal of Honor citation notes:

The President of the United States of America, in the name of Congress, takes pride in presenting the Medal of Honor (Posthumously) to Lieutenant Colonel John Upshur Dennis Page (ASN: 0-29085), United States Army, for conspicuous gallantry and intrepidity in action above and beyond the call of duty in a series of exploits while attached to the 52d Transportation Truck Battalion, in action against enemy aggressor forces at the Chosin Reservoir, North Korea, from 29 November to 10 December 1950. On 29 November, Lieutenant Colonel 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 Lieutenant Colonel 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 Lieutenant Colonel 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 two such attacks, Lieutenant Colonel Page exposed himself on the airstrip to direct fire on the enemy, and twice mounted the rear deck of a tank, manning the machinegun 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, Lieutenant Colonel Page dropped hand grenades on Chinese positions and sprayed foxholes with automatic fire from his carbine. After ten 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 Lieutenant Colonel Page was flown to Hamhung to arrange for artillery support of the beleaguered troops attempting to break out. Again Lieutenant Colonel Page refused an opportunity to remain in safety and returned to give every assistance to his comrades. As the column slowly moved south Lieutenant Colonel 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 Lieutenant Colonel Page manned the machinegun, 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, Lieutenant Colonel Page took a machinegun 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, Lieutenant Colonel 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 ten days, Lieutenant Colonel Page remained forward, fiercely engaging the enemy single-handed until mortally wounded. By his valiant and aggressive spirit Lieutenant Colonel Page enabled friendly forces to stand off the enemy. His outstanding courage, unswerving devotion to duty, and supreme self-sacrifice reflect great credit upon Lieutenant Colonel Page and are in the highest tradition of the military service.

His valor at the Chosin Reservoir was so incredible, the Marines among whom he served submitted him for the Navy Cross as well.

The President of the United States of America takes pride in presenting the Navy Cross (Posthumously) to Lieutenant Colonel John Upshur Dennis Page (ASN: 0-29085), United States Army, for extraordinary heroism in connection with military operations against an armed enemy of the United Nations while attached to the 52d Transportation Truck Battalion (Attached), X Corps Artillery, in action against enemy aggressor forces near Sudong-ni, Korea, on 10 December 1950. When numerically superior enemy forces ambushed a Marine regimental convoy with which he was traveling, Lieutenant Colonel Page repeatedly exposed himself to intense hostile machine-gun, mortar and small-arms fire to move forward in an effort to organize friendly elements and reduce the roadblock. Realizing the extreme danger to the stationary convoy while under the relentless fire of enemy forces commanding high ground on both sides of the road, he bravely fought his way to the head of the column accompanied by a Marine private and, undaunted by point-blank machine-gun fire, continued directly into the hostile strong-point, taking thirty of the enemy completely by surprise and inflicting severe casualties among them. With the Marine private wounded by a hand-grenade fragment, Lieutenant Colonel Page ordered him to withdraw and provided him with covering fire, fiercely continuing to engage the enemy single-handedly and killing twelve of them before he himself was mortally wounded. By his valiant and aggressive fighting spirit in the face of overwhelming odds during this self-imposed mission, he was directly responsible in disrupting the hostile attack, thereby allowing the members of the convoy to regroup, re-deploy and fight off succeeding attacks. His outstanding courage, self-sacrificing efforts and unswerving devotion to duty reflect the highest credit upon Lieutenant Colonel Page and the United States Armed Forces. He gallantly gave his life for his country.

LTC John U.D. Page became one of only three Army recipients of the Navy Cross in Korea.