The Battle of Lier (Norwegian: Slaget ved Lier) was fought on 2 August 1814 between Sweden and the newly independent Norway as part of the Swedish-Norwegian War of 1814. The battle was the first major action of the war, in which an outnumbered Swedish force attempted to storm the Norwegian entrenchment; the Norwegian victory served as an important part to boost morale among the Norwegian troops. This was the second time during the Napoleonic Wars that a battle had taken place at Lier, the first was in 1808.