The International Brigades (IB) were volunteer military units of foreigners who fought on the side of the Second Spanish Republic during the Spanish Civil War. The number of combatant volunteers has been estimated at between 32,000–35,000, though with no more than about 20,000 active at any one time. A further 10,000 people probably participated in non-combatant roles and about 3,000–5,000 foreigners were members of CNT or POUM. They came from a claimed "53 nations" to fight against the Spanish Nationalist forces led by General Francisco Franco and assisted by German and Italian forces.