Twenty-three currently active battalions of the Regular Army earned credit for campaigns during the War of 1812: two Air Defense Artillery battalions, six Field Artillery Battalions and seventeen Infantry battalions. These twenty-three battalions represent two Air Defense Artillery, four Field Artillery and seven Infantry regiments. Three additional Air Defense Artillery regiments have been awarded shared credit for War of 1812 campaigns, but the lineages of the artillery companies that earned those credits have not been perpetuated by currently active battalions. There are also twenty-four Army National Guard units with campaign credit for the War of 1812. Air Defense Artillery When the War of 1812 began, the Regular Army contained four regiments of artillery: the 1st, 2nd and 3rd Regiments of Artillery, and the Regiment of Light Artillery. In March 1814 the 1st, 2nd and 3rd Regiments were combined to form the Corps of Artillery, consisting of forty-eight companies; the Regiment of Light Artillery consisted of ten companies. Only a few companies from the 1st and 2nd Regiments of Artillery functioned regularly as "mobile" artillery, that is, in support of an infantry attack. Most of the time during the War of 1812 artillery was used as "position" artillery to repel an attack by enemy infantry. Artillery companies also often fought as infantry. Indeed, the 1st Regiment of Artillery served primarily as infantry in New York and along the Canada–US border, and the Regiment of Light Artillery, rather than functioning as a mobile horse artillery, was reorganized as infantry by the end of the war. During a major reorganization of the Army in 1821, the Corps of Artillery and the Regiment of Light Artillery were abolished, and four new artillery regiments were constituted: the 1st, 2nd, 3rd and 4th Regiments of Artillery. These four regiments were the precursors of the present-day 1st, 2nd, 3rd and 4th Air Defense Artillery Regiments. The four new regiments constituted in 1821 were organized from existing artillery companies that had served in the War of 1812. As a consequence, even though these four Air Defense Artillery Regiments do not trace their lineages back to artillery formations that existed during the War of 1812, all four have been awarded shared credit for War of 1812 campaigns because of the service of their component elements that do date back to the War of 1812 or earlier. Of the fourteen companies that survived into the twenty-first century as Air Defense