He was able to make his way back to friendly lines on the 19th and provided valuable information on German positions.
Private First Class Johnston's official Medal of Honor citation reads: For conspicuous gallantry and intrepidity at risk of life above and beyond the call of duty in action against the enemy.
All that day he manned his gun without relief, subject to mortar, artillery, and sniper fire.
Two Germans individually worked so close to his position that his machinegun was ineffective, whereupon he killed 1 with his pistol, the second with a rifle taken from another soldier.
When a rifleman protecting his gun position was killed by a sniper, he immediately moved the body and relocated the machinegun in that spot in order to obtain a better field of fire.