Staff Writer (Updated: 5/13/2016):
From 1915 to 1916, the United States Marine Corps (USMC) partnered with the Armored Motor Car Company (AMC) of Detroit to develop and produce an armored car system based on a King-branded luxury automobile chassis. USMC authorities envisioned a squadron of such cars supplying mobile machine gun firepower to advancing enemy troops, ultimately overwhelming the enemy and dislodging them from their trenches. The hull superstructure was designed by Captain W.A. Ross to which AMC manufactured the overall concept. The superstructure was mated to the King automotive chassis to form the "King Armored Car". From the outset, the vehicle would be used on a experimental basis intending to fill a need and prove concepts along the way. American had not officially entered the war in 1915 but plans for inevitable participation were not lost on some American authorities.
Two prototype King Armored Cars were evaluated on streets outside of Philadelphia beginning in 1915, becoming the first armored fighting vehicle (AFV) of the US armed forces. Initial evaluations proved the design underpowered, even on ideal roads, and the weight of the superstructure worked against the manual transmission which resulted in a sluggish responding vehicle. The original balloon rubber tires proved awkward in overall handling which led to the rear pair being replaced by a more robust double-tired configuration to help compensate for the added weight while increasing ground contact in turn. A slightly revised version with new turret then appeared and it was this version that was ordered by the USMC in 1916.
The King design was conventional for its time, utilizing six "balloon" type rubber-tired spoked wheels (with spares carried along the sides) in a 4x2 arrangement, a boxy armored superstructure with manually-traversing turret and a front-mounted engine. The vehicles were crewed between two to three personnel, one dedicated to its overall operation (including steering) while another serving the manually-traversing function of the armored turret emplacement and its supplied machine gun. Beyond the primary weapon, the crew relied on any personal weapons being carrier such as pistol sidearms. The superstructure allowed for protection from small arms fire (this proved with .45 pistol shots at close range) as well as artillery spray. There were armored vision ports along the front and sides of the structure with the turret emplacement sitting atop the flat superstructure roof. External shelving was installed along the sides of the hull to support various equipment. The typical rounded headlamps of the time were retained though housed behind hinged door-like horizontal armor plates that could be manually closed prior to battle. The engine grille was also covered in this way by a set of hinged vertical armored doors. A steel obstacle breaching installation was added to the front of the hull. Construction included riveting along its major armored steel plates and operational range was out to 200 miles with fording possible up to 14 inches of water. King Armored Cars were designed with transportability in mind, being able to disassemble prior to transport and reassembled once relocated.