Ham, a town in the French department of Somme, on the river of that name, 12 miles SW. of St Quentin. Its ancient fortress or castle was rebuilt by the Comte de Saint Pol in 1470, and now is used as a state-prison. It is memorable as the place of confinement of Joan of Arc, Monecy, and others; of Polignac, Peyronnet, and
Guernon de Ranville from 1831 to 1836; of Louis Napoleon from 1840 till 1846; and after the coup d'état, of the republican generals Cavaignac, Lamoricière, Changarnier, &c. Pop. 2837. See Gomard, Ham, son Château, &c. (1864).