Leon De Wolf was born c1841 in Hudson, New York and enlisted in New York City as an ordinary seaman on 31 May 1864 for a three year term. Per his rendezvous index card , he was attached to the West Gulf Blockading Squadron on 11 June 1864. At some point he was ordered to the USS Arizona.
On 13 April 1865, De Wolf was in command of a three-man working party that was tasked with minesweeping the Mobile River in front of the city when one of the mines they retrieved accidentally exploded, killing all three. From the CO of the Cincinnati, LCDR George Brown, report to Acting RADM Henry K. Thatcher of the incident:
United States Iron-Clad Cincinnati
Sir, I deeply regret to have to report the blowing up of the launch of this vessel by a torpedo yesterday afternoon.
By this sad accident three lives were lost. Their names are as follows: Acting Master's Mate Leon De Wolf, Captain of Forecastle C. H. Howard, Ordinary Seaman John Dreon. The launch had caught a torpedo, and had weighed it to within about two feet of the surface of the water, when the mooring parted, and the strain on the drag-rope brought the torpedo against the stern of the boat, exploding it.
I am, sir, respectfully, your obedient servant
Lieutenant Commander 
Leon De Wolf was about 23-24 years old and had been in the Navy for just over ten months.
Awards and Memorials
 Return of the United States Naval Rendezvous, New York, NY for the week ending June 4 1864
 NARA T1099. An index to rendezvous reports during the Civil War, 1861-1865.
 Letter from James Palmer to Gideon Welles. NARA M89. Letters Received by the Secretary of the Navy from Commanding Officers of Squadrons("Squadron Letters"), 1841-1886
 Letter from George Brown to H. K. Thatcher. NARA M89. Letters Received by the Secretary of the Navy from Commanding Officers of Squadrons("Squadron Letters"), 1841-1886