Mercader's contacts with and befriending of Trotskyists began during the Spanish Civil War. George Orwell's biographer Gordon Bowker relates how English communist David Crook, ostensibly a volunteer for the Republican side, was sent to Albacete. He was taught Spanish and also given a crash course in surveillance techniques by Mercader. Crook, on orders from the NKVD, used his job as war reporter for the "News Chronicle" to spy on Orwell and his Independent Labour Party comrades in the POUM (Workers' Party of Marxist Unification) militia.