In 1951, Prime Minister Sidney Holland faced a major challenge from the militant Waterside Workers' Union during the 1951 waterfront dispute (13 February – 11 July 1951). The 1951 waterfront dispute was sparked by the refusal of shipowners to give a 15 per cent wage rise to the watersiders who proceeded to ban overtime work. The shipowners retaliated by imposing a lock-out on striking workers. When the watersiders refused to accept arbitration, the National Government imposed emergency regulations under the 1932 Public Safety Conversation Act which drastically curtailed civic liberties, including the freedom of speech and expression. The Regulations were designed to silence and criminalise any support for the watersiders, including food supplies for their families, and pro-watersider publications. In addition, Holland ordered the armed forces to unload cargo from ports and deregistered the Waterside Union and seized its funds. After 151 days, the watersiders capitulated.