At first, Alba had little difficulty in repelling the rebel military incursions, led by William. However, maintaining a large military presence put severe strain on the royal finances, especially because Spain was fighting expensive wars against the Ottoman Sultan and in Italy at the same time. Alba's attempts to finance these expenses by new taxes also estranged previously loyal subjects from the royalist cause. Then, in 1572, a group of privateers with letters of marque from William (known as "watergeuzen") were unexpectedly successful in an invasion into Holland and Zeeland. Orange was able to take over the government in these two provinces under the guise of his old post of royal Stadtholder, and brought them into open revolt against the government in Brussels. This brought about a formal state of war between Holland and Zeeland and the fifteen loyalist provinces.