Seven Years War
1756-1763, often referred to as the first truly global war and a warm up act for the Napoleonic wars to follow in just 30 or so years.
The Prussians on the other hand started their remorseless 150 year climb to disaster, laying the foundations for their tactical genius and strategic imbecility. This is best summarized as "If we're going to have a war with the Russians and the French, what say we also build an Imperial navy just big enough to piss off the Brits but nowhere near big enough to beat them?" aka WW1.