Fox received the country's highest award for bravery during combat, the Medal of Honor, for his action during the Siege of Port Hudson in Louisiana on 14 June 1863.

While the exact date of his birth is uncertain, he was baptized on November 5, 1844, in the Roman Catholic church in Oldcastle.

He died on 2 October 1929 and his remains are interred at Saint Mary's Cemetery in Rye Brook, New York.

After several men had been killed in attempting to relieve the sufferings of the wounded, Fox volunteered to carry water to them, and loading himself with canteens made two trips in plain view and under the hot fire of the enemy, his act being praised at the time by his brigade commander.”The President of the United States of America, in the name of Congress, takes pleasure in presenting the Medal of Honor to Private Nicholas Fox, United States Army, for extraordinary heroism on 14 June 1863, while serving with Company H, 28th Connecticut Infantry, in action at Port Hudson, Louisiana.

Private Fox made two trips across an open space, in the face of the enemy's concentrated fire, and secured water for the sick and wounded.