Who started the construction of a fleet of gunboats and named US Grant in command of Cairo?

The popular frontiersman John C. Fremont ('The Pathfinder') who turned out unsuccessful as a General, and left a tangle of corruption to be sorted out by his successor, Henry Halleck.

IMPROVEMENT

John Frémont strongly supported the construction of the gunboats, but who was appointed by the Union Government to this purpose was Captain James B. Eads, an engineer and at the same time a mathematician, scholar of hydrography and a naval designer and builder. He won a public competition to build up a fleet of ironclads gun boats apt to be employed on riverine waters of 9 units in no more than 65 days.

The first unit, the Baron de Kalb was launched after 45 days and the remnants units were ready to be employed on time. The project was further developed by the building of two additional ironclads gun boats, Benton and Essex , which had been made out of the radical transformation of two old river vessels, and 38 "raft-boats", iron-shielded and suitable to carry a heavy mortar each one.