Born is Iowa in 1851, he was appointed to the Naval Academy from Iowa in July 1866 and graduated in 1871.  After leaving the Academy he was assigned to the Pensacola,  on the Pacific Station,  for 1871 to 1873, when he was given recruiting duty at Chicago for one year.  From 1874 to 1877 he was on the Home Station, and in the next he was on duty at the Naval Torpedo Station.  After spending three years on the Richmond, in the Orient, he returned to the United States in 1882, to take up ;duty at the Boston Navy Yard.  Then came his promotion to lieutenant.  In November, 1883, after which he spent three years in the Shenandoah, on the Pacific Station, returning to the Naval Academy in 1886 for three years.  In 18899 he was assigned to the Naval Intelligence Office for a year, following which he was given duty on the Baltimore until 1893, when he was assigned to the Bureau of Ordnance.

His next assignment was to the cruiser Brooklyn as Navigator.  Brooklyn played a prominent role in the Battle of Santiago during the Spanish-American War.

On July 15, 1907, while in command of the USS Georgia in Boston Harbor there was a disaster on board when 9-men were killed and 13-others injured.  While completing gunnery practice the aft-superimposed 8" gun turret a powder bag caught fire from hot embers and caused a detonation inside the turret.  Captain McCrea and Rear Admiral Charles Thomas on the bridge watch events as they unfolded.

Quoted in the New York Times on July 17th, Captain McCrea said, "I head a shout 'Fire!' but there was no shot, and then I saw men saw men running aft and quickly  the  fire hose that is  always laid out in the readiness when there is firing going on, was manned.  I  rushed to the after bridge, near the turret, to see what was the matter.  The water was already being poured into the turret.  The boatswain and Midshipman Gravescroft led the way for their men with the hose.  I tell you, there was courage.  No man knew what had happened and no man knew into what danger he might be rushing.   But those men never thought of self or danger.  That brave act will look well on their  record."