The Atlantic oligarchy reacted in a coordinated way to the upheavals which engulfed Scotland, Ireland and finally England, 1638–42. It made the financial arrangements that ended the Bishops’ Wars while securing the calling of the Long Parliament and then took the lead in reinforcing Protestant Ireland following the outbreak of the 1641 revolt. The colonial merchants emerged as a powerful force in London politics at the outbreak of the city’s rebellion against Charles I in January 1642. The central argument of this chapter is that the merchant networks that supported parliament’s opposition to the king were not operating independently, but were contractors to or under the patronage of specific peers. The key role of colonial sponsors and returned migrants from the colonies in the upheavals of the winter of 1641–42 is made clear. Alliances forged in the Atlantic world between 1620 and 1640 finally coalesced as a pivotal political and military force at the forefront of parliament’s ousting of Charles I from London in January 1642.