On the official announcement of the dual policy of Home Rule and conscription, Dillon and O’Brien led their party members out of the Commons and returned to Ireland. The Home Rulers united with Sinn Féin in the anti-conscription pledge of 21 April at the height of the Conscription Crisis, at the Dublin Mansion House Conference and the great one-day strike and demonstration of 23 April. Dillon believed that Lloyd George had 'let HELL loose in Ireland' as part of a Machiavellian plot to evade his promise to grant home rule. This radicalisation of the Home Rule movement came too late to stem the electoral swing. Arthur Griffith, founder of Sinn Féin, defeated the Home Ruler in the East Cavan by-election on 20 June.