In WWII Russia deployed radio controlled tanks in battle. From Popular Science:
Seventy-four years ago, Russia accomplished what no country had before, or has since—it sent armed ground robots into battle. These remote-controlled Teletanks took the field during one of WWII’s earliest and most obscure clashes, as Soviet forces pushed into Eastern Finland for roughly three and a half months, from 1939 to 1940. The Finns, by all accounts, were vastly outnumbered and outgunned, with exponentially fewer aircraft and tanks. But the Winter War, as it was later called (it began in late November, and ended in mid-March), wasn’t a swift, one-sided victory. As the more experienced Finnish troops dug in their heels, Russian advancement was proving slow and costly. So the Red Army sent in the robots.
Specifically, the Soviets deployed two battalions of Teletanks, most of them existing T-26 light tanks stuffed with hydraulics and wired for radio control. Operators could pilot the unmanned vehicle from more than a kilometer away, punching at rows of dedicated buttons (no thumbsticks or D-pads to be found) to steer the tank or fire on targets with a machine gun or flame thrower. And the Teletank had the barest minimum of autonomous functionality: if it wandered out of radio range, the tank would come to a stop after a half-minute, and sit, engine idling, until contact was reestablished.
More detail here..
The "tail" at the beginning of a technology can be very long. Many ideas are well ahead of their time - and many more simply never pan out.