Unlike more traditional wars there wasn't one central target to attack that could turn the tide of war. It was assumed that if you captured a nation's (symbolically) capital that could push a war to its conclusion.

The British found it extremely difficult to raise troops to fight this war - — and that is that the British found it extremely difficult to raise troops to fight this war.  German mercenary troops from a number of different independent German states, and they end up getting lumped under the heading "Hessian.