Russia Westphalia, Hesse and Lower Saxony Electoral Saxony Brandenburg Silesia East Prussia Pomerania Iberian Peninsula Naval Operations The Battle of Gross-Jägersdorf (30 August 1757) was a victory for the Russian force under Field Marshal Stepan Fyodorovich Apraksin over a smaller Prussian force commanded by Field Marshal Hans von Lehwaldt, during the Seven Years' War.

Empress Maria Theresa of Austria had signed the treaty to gain time to rebuild her military forces and forge new alliances; she was intent upon regaining ascendancy in the Holy Roman Empire as well as the Silesian province.

Seeing the opportunity to regain her lost territories and to limit Prussia's growing power, Austria put aside the old rivalry with France to form a new coalition.

Faced with this turn of events, Britain aligned herself with the Kingdom of Prussia; this alliance drew in not only the British king's territories held in personal union, including Hanover, but also those of his relatives in the Electorate of Brunswick-Lüneburg and the Landgraviate of Hesse-Kassel.

Prussia had achieved spectacular victories at Rossbach and Leuthen and reconquered parts of Silesia that had fallen back to Austria.

Ferdinand evicted the French from Hanover and Westphalia and re-captured the port of Emden in March 1758; he crossed the Rhine, causing general alarm in France.

[9] The Russian field marshal Stepan Fyodorovich Apraksin commanded an army of approximately 55,000 men and crossed the Niemen.

[16] The Prussians achieved a surprise attack, seized a number of positions from numerically superior forces and inflicted equivalent losses.

[20] In the aftermath, it was popularly expected in Russia that Apraksin would pursue the Prussian retreat and eventually overrun all of East Prussia; he was, after all, only 50 kilometres (31 mi) away from the Königsberg.

Historians offer several reasons: after hearing a false report that Empress Elizabeth of Russia had died; to support Peter III as heir to the throne;[21] Apraxin marched on Königsberg but his troops, lacking in supplies, suffered considerable attrition;[22] and, finally, an epidemic of smallpox, which hit the Russian army, especially the Kalmyks, and resulted in 8.5 times more deaths than all the battles fought in 1757.

[18] Recent research suggests that the Russians were entirely unprepared for war beyond their western border and had not realistically evaluated their potential supply problems in East Prussia.

Furthermore, the Russians had made no effort to expand their supply depots using the Baltic's seaports, which would have been the most obvious way to feed that number of troops at that distance.

[23] Once the Russians reached Livland, observers noted exhausted troops hauling carts because their horses, living on a diet of oak leaves, dropped dead by the hundreds every day.

This, though, attracted aspersions from his political enemies in St. Petersburg, who claimed he was wasting the imperial treasury; however, Fermor was considerably more successful in 1758 than his predecessor had been in 1757.