pre-War of Independence As a young adult Jacob become involved in organisations such as the
Gaelic League, the
Irish National League, and
Inghinidhe na hÉireann, a dedicated women's radical nationalist organisation. She, along with her brother Tom, was a member of
Sinn Féin from 1905, and it was Rosamond who opened the first branch of Sinn Féin in Waterford in 1906. It was that same year Rosamond became an
Irish language speaker and writer, a language she'd go on to become fluent in. Jacob's time in the Gaelic League over time began to grate, however, as she began to find the Catholic atmosphere there stifling to her developing feminist and agonist beliefs. In 1908 she joined the
Irish Women's Franchise League, created by her friend and fellow feminist
Hanna Sheehy-Skeffington. It was during this time she shared a cell with
Dorothy Macardle, now also firmly on the Republican side. Between 1920 and 1927, Jacob was secretary of the Irishwomen's International League, which had begun life in 1916 as the Irish branch of the
Women's International League for Peace and Freedom (WILPF). She and her colleague Lucy Kingston were the two Irish delegates to the Third International Women's Congress for Peace and Freedom in Vienna in 1921. She was among the organisers of the congress held in Dublin in 1926. It was also in 1926 that she followed De Valera and
Countess Markievicz and their supporters out of Sinn Féin and into the
Fianna Fáil party following a split over the policy of using
Abstentionism against
Dáil Éireann. In 1927 Jacob resigned as secretary of the Irish branch of the WILPF but went on to attend the organisation's congress in Prague in 1929 accompanied by
Hanna Sheehy-Skeffington. She played a leading role in the political campaign to secure Ryan's freedom from Nationalist Spain, and later worked to defend his reputation after news of his death in Nazi Germany became known. ==Writing==