From the mid-19th century women began to campaign for the vote across the country, and in 1897 local societies united to form the National Union of Women's Suffrage Societies. Led by Millicent Fawcett, the NUWSS grew to 50,000 members by 1913. The suffragists used peaceful methods such as petitioning, lobbying, and marching. In 1903, the Women's Social and Political Union was founded, led by Emmeline Pankhurst. It used direct action, including stone-throwing and window-breaking, and in June 1908 tried to 'rush' the Houses of Parliament. Many militant campaigners, known as suffragettes, were imprisoned, went on hunger strike, and were force-fed. The first woman to be elected to the House of Commons was Constance Markievicz in 1918, but she refused to take her seat as she was a Sinn Fein member and would not swear allegiance to George V. In 1919, Nancy Astor was the first woman to take her seat as MP for Plymouth Sutton. Women were allowed to sit in the House of Lords as life peers from 1958. Five years later, hereditary women peers were allowed to sit, and formal parliamentary equality was achieved. Margaret Bondfield became the first female Cabinet Minister in 1929, and a woman finally reached the top of Government in 1979, when Margaret Thatcher became the first female Prime Minister.