The Fenians were supplanted by the Clan na Gael, a secretive organization which raised funds during the War of Independence and pressured the American government to recognize an Irish Republic. The Clan supplied the Irish with money and weapons during the War of Independence.
In 1939 Sean Russell, the IRA’s Chief of Staff, toured America giving speeches and raising funds. His arrest in Michigan by federal authorities was protested by Irish-American Congressmen.
With the reemergence of the IRA in the 1970s Irish-Americans supplied arms and called for British withdrawal from Northern Ireland. By the end of the 1970s British authorities determined that eighty percent of the IRA weapons seized originated in the United States.