The <a href="https://en.wikipedia.org/wiki/M1_Combat_Car" class="extiw" title="w:M1 Combat Car">Combat Car, M1</a>, a U.S. Army <a href="https://en.wikipedia.org/wiki/light_tank" class="extiw" title="w:light tank">light tank</a> that was introduced in 1935 and entered service in 1937. It was used by the Army's cavalry branch and was designated as a "combat car" to circumvent a law which restricted tanks to the infantry. It was armed only with machine guns.
U.S. Army, <a href="https://en.wikipedia.org/wiki/Ordnance_Corps_(United_States_Army)" class="extiw" title="w:Ordnance Corps (United States Army)">Ordnance Department</a>
<a href="https://en.wikipedia.org/wiki/Army_Ground_Forces" class="extiw" title="w:Army Ground Forces">Army Ground Forces</a>, Board No. 2 (1 September 1947). <i><a rel="nofollow" class="external text" href="http://cgsc.cdmhost.com/cdm/ref/collection/p4013coll11/id/2071">Development of Armored Vehicles, Volume I: Tanks</a></i>, p. 68.