During Napoleon's invasion of Russia in 1812, Gruzinsky organized and headed the Nizhny Novgorod militia, which amounted to 12,440 men and fought under General Nikolay Muromtsyev against the Grande Armée until the fall of Paris in 1814. After the war, Gruzinsky spent the rest of his life in Lyskovo, dispensing charity. In the 1820s, he hosted and supported Anton II, a Georgian prelate dispossessed by the Russian authorities of his office. In 1852, Gruzinsky died at the age of 89 at his estate, allegedly in a fury at the sight of a peasant entering his house with a hat. He was interred at a familial burial ground at the Transfiguration Church of Lyskovo.