During the French invasion of Russia, he financed and commanded the creation of the 21st Lithuanian Infantry Regiment of the Army of the Duchy of Warsaw, which he led since 29 August 1812.[5] He took part in the defence of Modlin fortress. For his contributions to the French campaign, he was awarded the rank of colonel.
He defeated the Russians in the Battle of Rajgród, but his assault of Vilnius failed and his corps composed of his own division and the forces of Dezydery Chłapowski lost over 2,000 men in the battle of Paneriai. Unable to return to Polish-Lithuanian main forces at that time converging on Warsaw, he decided to head to Klaipėda, where he was expecting foreign reinforcements. En route, however, all three of Giełgud's columns were intercepted by the Russians and forced to cross the Prussian border. Giełgud himself soon after crossing the border was shot dead by one of his staff officers, enraged by his poor command.[6] He died on 31 August 1831 in the Šnaukštai [lt] village while crossing the Agluona river, where he was buried.[1][2]
Three to five years after the uprising, the Tsar of Russia agreed to transfer the remains of Giełgud to a cemetery in Kisiniai [lt], 10 kilometres (6.2 mi) from Klaipėda. Giełgud's grave was abandoned up until 1928 or 1929 when representatives of the noble family from the United Kingdom sent over money with a request to the eldership to clean up his grave. It was decorated with a cross, and became a gathering spot for the youth.[2] Giełgud's rebellious legacy is still celebrated to this day.[7][3]
^Feliksas Sliesoriūnas. Antanas Gelgaudas. Universal Lithuanian Encyclopedia, T. VI (Fau-Goris). - Vilnius: Institute of Science and Encyclopedia Publishing, 2004. 510 p.