Leake served under Sir Cloudesley Shovell and the Earl of Peterborough at the Siege of Barcelona and was present at the capitulation of the city by French and Spanish forces in October 1705. A further siege took place between in April 1706 when a Franco-Spanish army led by Philip V of Spain laid siege to Barcelona in an attempt to recapture it. The Franco-Spanish army abandoned the siege when Leake arrived in May 1706. On the way back, he supported operations to capture Cartagena in May 1706, Alicante in July 1706, Ibiza in September 1706 and Majorca later that month. Leake was promoted to full admiral, appointed Commander in Chief of the Mediterranean Fleet and given authority to fly the flag of an Admiral of the Fleet on 8 January 1708.