The Ingrian War (Swedish: Ingermanländska kriget) was a conflict fought between the Swedish Empire and the Tsardom of Russia which lasted between 1610 and 1617. It can be seen as part of Russia's Time of Troubles, and is mainly remembered for the attempt to put a Swedish duke on the Russian throne. It ended with a large Swedish territorial gain (including Ingria) in the Treaty of Stolbovo, which laid an important foundation to Sweden's Age of Greatness.

During Russia's Time of Troubles, Vasily IV of Russia was besieged in Moscow by the supporters of the False Dmitry II. Driven to despair by the Polish intervention, he entered into an alliance with Charles IX of Sweden, who was also waging war against Poland. According to the Vyborg Treatise of 1609, the tsar promised to cede Korela Fortress to Sweden in recompense for military support against False Dmitry II and the Poles. Russia also renounced all territorial claims on the coast of the Baltic Sea coast. The Swedish commander Jacob De la Gardie joined his forces with the Russian commander Mikhail Skopin-Shuisky and marched from Novgorod towards Moscow in order to relieve the tsar. In May, the De la Gardie campaign began, where the Swedish corps fought as part of the army of Skopin-Shuisky, who managed to clear a significant part of Russia from the interventionists.

Sweden's involvement in Russian affairs gave King Sigismund III Vasa of Poland a pretext to declare war on Russia. After the sudden death of Skopin-Shuisky, De la Gardie's troops were united with Shuisky's army, and the Poles defeated the combined Russo-Swedish force at the Battle of Klushino on 4 July [O.S. 24 June] 1610. The Swedish mercenaries taking part in the De la Gardie Campaign surrendered and De la Gardie concluded an agreement with Polish hetman Stanisław Żółkiewski. The battle had serious consequences for Russia, as the tsar was deposed by the Seven Boyars and the Poles occupied the Moscow Kremlin, after which the Russian state began to fall into its constituent parts. De la Gardie then sought to take control of the Russian north-west in order to prevent the Poles from extending their power and therefore threaten Sweden with an offensive on its Baltic territories.

In July 1611, a Swedish expeditionary corps under Jacob De la Gardie captured Novgorod. He compelled the Novgorodians to acknowledge the Swedish king as their patron and forced them to choose one of his sons, Carl Filip or Gustavus Adolphus, to be installed as their monarch.

Meanwhile, Gustavus Adolphus ascended to the Swedish throne. The young king decided to pursue his brother's claim to the Russian throne, even after the Poles had been expelled from Moscow by a patriotic uprising in 1612, which resulted in Mikhail Romanov being elected as the new tsar. He became the first tsar of the House of Romanov.

While Swedish statesmen envisioned the creation of a Trans-Baltic dominion extending northward to Arkhangelsk and eastward to Vologda, De la Gardie and other Swedish soldiers, still holding Novgorod and Ingria, viewed the war as a response to their forces not receiving payment for their support during the De la Gardie Campaign.

In 1613, Swedish troops advanced towards Tikhvin and laid siege to the city but were ultimately repelled. The Russian counteroffensive failed to reclaim Novgorod; however, the Russian tsar refused to commit his troops to battle, and the war dragged on until 1614 when the Swedes captured Gdov. The Swedes transferred about 5,000 soldiers who had participated in the Swedish-Danish war, which concluded with the peace in Knäred that same year. In 1614, an additional 7,000 soldiers were also shipped over.

The following year, Gustavus Adolphus laid siege to Pskov, but Russian Generals Morozov and Buturlin successfully defended the city. Sweden and Russia began negotiations on 9 March [O.S. 27 February] 1617, which ultimately resulted in the end of the war with the Treaty of Stolbovo.