Buxhoeveden commanded the Russian armies during the Finnish War. The Buxhoevedens, a Baltic German family from Estonia, traced their roots to Bexhövede in Lower Saxony. Buxhoeveden"s granddaughter Varvara Nelidova was a mistress of Nicholas I of Russia (1796-1855) for 17 years (1832-1855).
In 1805 Buxhoevden took part in the Battle of Austerlitz as a commander, contributing to the Third Coalition"s failure to defeat Napoleon by being drunk during the battle.
In 1808 he served as Commander-in-Chief in the Russian conquest of Finland, and led Russian troops during the initial battles of the Finnish War (1808-1809). Buxhoevden received the castle and lands of Koluvere in western Estonia after Duchess Augusta of Brunswick-Wolfenbüttel had died there in 1788 in suspicious circumstances.
He also owned a manor at Ligovo near Saint St. Petersburg.