John Charles Philip DeKrafft was born in Washington, District of Columbia, on January 12, 1828. He was appointed Cadet Midshipman on October 19, 1841, and was graduated from the US Naval Academy, Annapolis, with the second group of Midshipmen to be graduated from that newly established institution, most of whom had had their pervious training (before 1745) at the Navy Yard, Philadelphia, and other Yards. Before final graduation, he served for the two years at sea, then required by law, and on August 10, 1847, was warranted Passed Midshipman. He subsequently was promoted as follows: Lieutenant September 15, 1855; Lieutenant Commander, July 16, 1862; Commander, July 25, 1866, Captain, November 20, 1872; Commodore, October 1, 1881; and Rear Admiral, from June 2, 1885.
From 1846 until 1860 he cruised in the Mediterranean, Pacific, Brazil and Home Squadrons, in various ships including the steamer Michigan, on the Great Lakes, and sloop John Adams in Pacific waters. At the beginning of the Civil War in 1861, he was on special service in USS Niagara, which took part in attacks on Fort McRee and Pensacola, Florida, on November 22-23, that year. He was assigned to the Navy Yard, Washington, DC in 1862, and during the next two years he commanded USS Conemaugh (third rate paddle-wheel gunboat) in operations in Lake Pontchartrain and Mississippi Sound. In 1864-1865 he served with the West Gulf Blockading Squadron, still in command of the Conemaugh, and successfully cooperated with the Army in operations against Fort Powell, causing the American Flag to be hoisted on that Fort, August 5-6, 1864.
In 1865 he took the Conemaugh to Philadelphia for repairs, and during 1866-1868 had special duty at Philadelphia. On February 18, 1868, he became Chief of Staff to the Commander North Atlantic Squadron, and in 1869 was made Fleet Captain of that Squadron. On October 12, 1869, he returned to Philadelphia, for Special Duty, and on September 23, 1870, reported to the Navy Yard, Portsmouth, New Hampshire, for Equipment Duty.
In the rank of Captain, from November 1872, he commanded USS California, Flagship of North Pacific Station, and in 1873 was transferred to command of USS Richmond, also assigned to North Pacific Station. From May 1, 1874, until March 1, 1875, he commanded USS Hartford, Flagship of Commander, Asiatic Station. He was then granted a leave of absence from March 1, 1875 to November 5, 1877, and during that period was at his home in Wilmington, Delaware. He next had shore duty at the Navy Yard, Washington, DC, after which, from July 12, 1880, until June 1883, he served as Hydrographer of the Navy, attached to the Bureau of Navigation, Navy Department, Washington, DC.
On August 22, 1883, he assumed his last duty, that of President of the Board of Inspection, Navy Department. He was serving in that capacity when promoted to Rear Admiral on June 2, 1885, and at the time of his death on October 29, 1885, in Washington. He was burried in Arlington National Cemetery, Arlington, Virginia.