This glider was designed to carry a tank. however, the only tank it was designed to carry was a specially-designed light tank, called the "Tetrarch". Unfortunately, the little Tetrarch was too lightly armed and armored for the battlefield of 1944, and would have been of little use. I believe most of the Hamilcar gliders were employed for the transport of more useful items, such as jeeps and anti-tank guns.
The whole concept of military assault by means of gliders died out not long after WW-II ended, largely due to the introduction of helicopters. By the time of the Vietnam War glider-borne infantry had been replaced in the U.S. Army by so-called "Air Cavalry", which were essentially helicopter-borne infantry.