'Britain in Ireland is a beast exceeding terrible; his feet and claws are of iron,' The Invincibles In an Ireland still reeling from years of famine, with tenant farmers being evicted and left to starve for their inability to pay exorbitant rents, revolutionary fervour was growing. An inner circle of the IRB was formed, a secret assassination squad within a secret society – the Irish National Invincibles. Their mission was to strike at the heart of British Imperial power, to kill the figureheads of Ireland's oppressors. On their way home from a triumphal parade through the city, Lord Frederick Cavendish and Thomas Burke, two of the heads of the establishment, were set upon and stabbed to death in the Phoenix Park. These killings would shake the Empire to its core, and shape the following decades of Irish history.