He was one of the few devoted supporters of Chancellor Aleksey Bestuzhev, who ensured Apraksin's promotion to Field Marshal and appointment to command the Russian army on the outbreak of the Seven Years' War in 1756.

The next year Apraksin took up the overall command of the army invading Prussia and won the Battle of Gross-Jägersdorf on 30 August 1757, albeit with heavy losses.

Instead, on hearing that Empress Elizabeth had suffered a severe relapse in health, Apraksin crossed the Neman River and returned to Russia, intending to support the heir to the throne (the future Peter III of Russia, who represented the interests of Frederick II of Prussia) in the event of the Empress's death.

As Elizabeth recovered, Bestuzhev fell from power and suffered banishment, and Apraksin came under the suspicion of having received bribes from the Prussian king.

Put on trial, he died in prison under mysterious circumstances in August 1758 before the military tribunal had reached a decision as to the reasons for his scandalous retreat.