De la Gardie was an advocate of peace with Poland and acted as one of the Swedish negotiators at the Truce of Stuhmsdorf in 1635. De la Gardie became a member of the Swedish Privy Council in 1613. In 1620, he became Lord High Constable and, as such, he was later one of the five regents ruling Sweden during Queen Christina's minority (1632–44). His pacifist and pro-French and pro-Polish attitudes often put him at odds with Chancellor Axel Oxenstierna, who led Sweden's war effort in the Thirty Years' War after the death of Gustavus Adolphus in 1632. As De la Gardie supported many of Oxenstierna's other policies, eventually the two leaders reconciled after Oxenstierna's return to Sweden in 1636. Although the Marshal's Office came under criticism that year, De la Gardie continued to operate effectively, making large profits from leasing royal revenues and from loans to the crown. In 1618, De la Gardie married Ebba Brahe, the love of young Gustavus Adolphus. The couple had 14 children, the most famous among them being Magnus Gabriel De la Gardie, Maria Sofia De la Gardie, Axel Julius De la Gardie and Countess Christina Catharine De la Gardie (1632–1704), who married Gustaf Otto Stenbock and was mother of Magnus Stenbock. Count Jacob De la Gardie died in Stockholm in 1652 and is buried in the Veckholm Church in Uppsala County, Sweden. The city of Jakobstad in Finland is named after him. A shopping mall in Old Tallinn is named "De la Gardie" in honor of him. During the Ingrian War, the Finnish soldiers nicknamed their commander "Laiska-Jaakko" ("Lazy Jacob"), due to the unusually lengthy six-year occupation of Novgorod. This name is still widely remembered in Finland. The siege was thus recorded in a folk verse: "Lähti suvi, lähti talvi, vaan ei lähde Laiska-Jaakko." ("The summer left, the winter left, but Lazy Jacob does not leave.")