The last election of an O'Dowd Taoiseach took place in 1595. By this time they were simply a client clan of the O'Connor clan of Sligo. This coincided with the Nine Years War, when the last independent Irish clans rose to resist English occupation of Ulster. The clan played an honourable role in the war, assisting Hugh Roe O'Donnell, in defending the western border of Ulster from incursions by the Earl of Essex in 1599 (most probably at the Battle of Curlew Pass). With the Irish defeat in 1603, their power rapidly dwindled and they were deprived of most of their patrimonial possessions. Daithi Óg O'Dowd, who married in 1636, was the last generation of O'Dowds given by MacFirbis in his pedigree of the clan. This also coincides with historical events – namely the Cromwellian reconquest (1642) following Ulster's 1641 revolt.