The Stridsvagn 103 (strv 103), [Note 1] also known as the S-Tank,[Note 2] was a Swedish post-war main battle tank. It was known for its unconventional design: it was turretless with a fixed gun traversed by engaging the tracks and elevated by adjusting the hull suspension. While turretless armoured fighting vehicles are usually classified as assault guns or tank destroyers, despite its unique gun laying process the Strv 103 is considered a tank because its designated combat role matched those of other tanks within contemporary Swedish doctrine. It is the only tank of any kind since World War II to dispense with a turret.
Additional Information: en.wikipedia.org/wiki/Strv_103