Under the 1729 Treaty of Seville, the British had agreed not to trade with the Spanish colonies. To verify the treaty, the Spanish were permitted to board British vessels in Spanish waters. After one such incident in 1731, Robert Jenkins, captain of the ship Rebecca, claimed that the Spanish coast guard had severed his ear. The British government, which was determined to continue its drive toward commercial and military domination of the Atlantic basin, used this incident as an excuse to wage war against Spain in the Caribbean. In 1738 Jenkins exhibited his pickled ear to the House of Commons, whipping up war fever against Spain. To much cheering, the British Prime Minister, Robert Walpole, reluctantly declared war on 23 October 1739.