In the mid-1560s, during the conflict between the English and Shane O'Neill, there were proposals to colonize parts of east Ulster, but Crown support was not forthcoming. The Crown eventually agreed to support a plantation in eastern Ulster in the 1570s, which ultimately failed. The east of the province (occupied by the MacDonnells and Clandeboye O'Neills) was intended to be colonised with English planters, to establish a barrier between the Gaels of Ireland and Scotland, and to stop the flow of Scottish mercenaries into Ireland. The conquest of east Ulster was contracted out to the Earl of Essex and Sir Thomas Smith. The O'Neill chieftain, Turlough Luineach O'Neill, fearing an English bridgehead in Ulster, helped his O'Neill kinsmen of in Clandeboye. The MacDonnells in Antrim, led by Sorley Boy MacDonnell, also called in reinforcements from their kinsmen in the Western Isles and Highlands of Scotland.