The M41 Walker Bulldog, named for Army General Walton Walker, entered service in 1953 during the Korean War as an agile, well-armed American light tank, but its weight, fuel consumption, and loud engine noise limited its combat use with the U.S. Army in that conflict. During the Vietnam War it was used primarily for internal security missions and was initially successful against North Vietnamese armor, but after the North Vietnamese Army commissioned the Russian T54 tank, the Walker Bulldog's gun proved ineffective against its heavy armor. The M41 was eventually replaced by the M551 Sheridan Light Tank. Built in the United States, the tank weighed 23.5 tons, had a four-person crew, 1.5-inch steel armor, a 76 mm M32 gun, .50 caliber and .30 caliber machine guns, a 500 horsepower engine, an operational range of 100 miles, and a top speed of 45 mph.