He served in various capacities in the Civil War, and in1865-1867was a member of the state House of Representatives, becoming secretary of the commonwealth in1873-1878and again in 1879-1882, recorder of Philadelphia in 1878-1879, and state treasurer in 1886-1887.
Deane's capacities and activities were now required for the navy.
Upon the conclusion of the treaty he went to Stockholm as plenipotentiary; and in both capacities he behaved with resolution and address.
Between 1858 and 1868 he was employed in home waters on a variety of special services, chiefly connected with gunnery, signalling and the tactical characteristics and capacities of steam warships.
But while there was no doubt as to the shooting capacities of these guns, defects in the breech mechanism soon became equally patent, and in a few years caused a reversion to muzzle-loading.