Similarly, in May 1920, Dublin dockers refused to handle any war matériel and were soon joined by the Irish Transport and General Workers' Union, who banned railway drivers from carrying members of the British forces. Blackleg train drivers were brought over from England, after drivers refused to carry British troops. The strike badly hampered British troop movements until December 1920, when it was called off. The British government managed to bring the situation to an end, when they threatened to withhold grants from the railway companies, which would have meant that workers would no longer have been paid. Attacks by the IRA also steadily increased, and by early 1920, they were attacking isolated RIC stations in rural areas, causing them to be abandoned as the police retreated to the larger towns.