Coughlin received the country's highest award for bravery during combat, the Medal of Honor, for his action at Swifts Creek in Virginia on 9 May 1864.

He was appointed as Lieutenant Colonel of the 10th New Hampshire Volunteer Infantry in September 1862, and mustered out with the regiment in June 1865.

He received a brevet (honorary promotion) to brigadier general dated 9 April 1865 for "gallant conduct in the field".

He died on 27 May 1912, and his remains are interred at the Arlington National Cemetery in Virginia.

[4] During a sudden night attack upon Burnham's Brigade, resulting in much confusion, this officer, without waiting for orders, led his regiment forward and interposed a line of battle between the advancing enemy and Hunt's Battery, repulsing the attack and saving the guns.