Between 1746 and 1748 Pitt worked closely with Newcastle in formulating British military and diplomatic strategy. He shared with Newcastle a belief that Britain should continue to fight until it could receive generous peace terms, in contrast to some such as Henry Pelham who favoured an immediate peace. Pitt was personally saddened when his friend and brother-in-law Thomas Grenville was killed at the naval First Battle of Cape Finisterre in 1747. However, this victory helped secure British supremacy of the sea which gave the British a stronger negotiating position when it came to the peace talks that ended the war. At the Treaty of Aix-la-Chapelle in 1748 British colonial conquests were exchanged for a French withdrawal from Brussels. Many saw this as merely an armistice and awaited an imminent new war.