The military build-up was accompanied by diplomatic measures in Portugal aimed at securing King Peter II for the Grand Alliance. The Allies also intended to garner support in Spain for an insurrection in the name of the Austrian pretender to the Spanish throne, the Archduke Charles. The battle was the first of the war in the Iberian Peninsula, but due to Allied intra-service rivalry, ill discipline, poor co-operation, and a skilful defence from the Marquis of Villadarias, Admiral George Rooke was unable to complete his objective and, after a month, he set sail for home.