In the Seven Years War the lowest estimate of casualties is 900,000 and other sources go as high as 1.4 million. This war was between Prussia and an alliance of France, Austria, and Russia. The French and British also fought mostly at sea in this same time period (1756-1763), although, they were fighting an almost completely different war between each other. A Prussian commander named Frederick the Great said this, "It's easier to kill these Russians that it is to defeat them," after the battle of Zorndorf (25 August 1785)
P.S. I am unsure on all the dates seeing as my book is a little unclear.
P.S. I am unsure on all the dates seeing as my book is a little unclear.