Today in 1972, US Patent 3670929 A was issued, an invention of Harry E. Berry, for his “Beverage Dispensing Keg.” Here’s the Abstract:

A beer keg construction having only a single access aperture opening midway between the top and bottom of the side wall of the keg with first and second male component quick-connect connectors being mounted inwardly of the aperture in the keg on an endwall of a cylindrical cup-like support member which can be removed from the aperture to enable cleaning and filling of the interior of the keg and with two female component quick-connect connectors on a pressure hose and lager hose being connectable to the male component connector members to enable liquid dispensing and keg pressurization with a minimum of difficulty.