On 8 February 1587, the execution of Mary, Queen of Scots outraged Catholics in Europe, and her claim on the English throne passed (by her own deed of will) to Philip. In retaliation for the execution of Mary, Philip vowed to invade England to place a Catholic monarch on its throne. In April 1587 Philip's preparations suffered a setback when Francis Drake burned 37 Spanish ships in the harbour of Cádiz, and as a result the invasion of England had to be postponed for over a year.