The Czechs certainly delved into armored car design and development almost as soon as their Army was arranged after the close of World War 1 (1914-1918). There were several notable attempts including the PA-II "Turtle" which led to the PA-III, also known under the designation of "OA vz. 27". This vehicle entered service in 1927 and was part of the Czech inventory when the Germans rolled in during 1939. The stock was used by Nazi German elements as well as Romanian and Slovakian forces before the end. The last but of recorded information on the series was in 1944 by which point many were either scrapped or destroyed. A total of sixteen cars were produced including a sole prototype based on design work spanning from 1925 to 1927. The manufacture was the fabled Skoda Works of Czechoslovakia.
As built the vehicle exhibited a 6.6 tonne weight and held a length of 5.35 meters, a width of 1.95 meters and a height of 2.6 meters. It was crewed by five and armed through 2 x 7.92mm Schwarzlose MG vz. 07/24 series machine guns (water-cooled) as primary armament in a roof-mounted turret and 1 x 7.92mm ZB vz. 26 series machine gun (water-cooled) in a trainable mounting overlooking the rear. Armor protection reached 5.5mm in thickness and drive power came from a single Skoda 4-cylinder gasoline-fueled engine fitted to the forward-most section of the design. Both axles were suspended in the four-wheeled arrangement. Operational ranges were out to 250 kilometers with road speeds reaching up to 35 kilometers per hour.
Like other Czech car designs, the OZ vz. 27 held two driver positions (one forward, one aft) so the vehicle could be driven in either direction without the car having to be completely turned around - thus saving critical seconds in a hasty escape. Either set of wheels were steerable depending on which driver position held control at the moment. This two-driver position was debuted in the earlier PA-I series car and remained a special attribute of Czech armored cars from then on. A steel internal frame was used to support the riveted armor plating. Access for the crew was through side-mounted hinged doors and a turret-roof-mounted hatch. Vision slots were accordingly cut into the armor at various positions about the hull to provide some basic situational awareness.
In many ways the OA vz. 27 was intended as an improvement over the PA-I and PA-II series cars which all held their own specialized limitations. The newer offering promised to be budget- and production-friendly and dimensionally compact while retaining many of the strong features of the preceding designs. Maintenance was improved as was reliability and crew comfort while the machine guns carried optical sighting devices for accurized fire at range. Despite this the vehicle tipped the scales in the wrong direction and was deemed overweight for the powerplant installed and the role intended. Manufacturing cost was also a detrimental quality and this led to only limited production being had. - fifteen cars followed the one prototype.
One in practical service, the car gave a good showing in terms of reliability. It reinforced sections of existing Czech Army cavalry and armored regiments and early use saw them in riot control duties. Then came border issues with Hungary and Poland where the OA vz. 27 was pressed into service as security and, in March of 1939, Slovakia declared its independence from Czechoslovakia which led to three of the cars escaping to Romania (two were later destroyed in an Allied air raid of 1944) and three fell to the newly-formed Slovakia where they were used for training. At least nine were known to have been taken over by the conquering Nazis at Bohemia-Moravia and most likely used for training if not for local security.