However, the Scots were increasingly concerned at their loss of political and economic power since 1603. In an effort to mitigate this, during the 1642–1645 First English Civil War, the Covenanters agreed the 1643 Solemn League and Covenant. One outcome was the creation of the Committee of Both Kingdoms, a union of English and Scottish parliamentary leaders; opposed by English Royalists and Oliver Cromwell, it was suspended in 1645. In 1647, the Scots agreed to restore Charles to the English throne; their failure in the 1648–1649 Second English Civil War led to his trial and execution by the English Rump Parliament and officers of the New Model Army.