In the modern age of missiles we can fire at targets over the horizon, and a seemingly limitless suite of radar, infrared, and optics technologies designed specifically to keep our pilots aware of everything going on around them, one could be forgiven for forgetting that there was a time when military aviation relied almost solely on what a pilot could see with the naked eye. In the early days of aerial combat, you couldn’t hit what you couldn’t see, and combat aviation training reflected that by placing a reduced emphasis on preparing for airborne missions under cover of darkness. After all, if you couldn’t see, neither could your opponent, so nations tended to limit their dogfighting to the daylight hours.

Today, we roll our eyes at the outrageous price tags associated with each F-35 pilot’s helmet, designed specifically to ensure the pilot has total situational awareness that extends for miles in every direction. This is essential for the success of the F-35 in combat, as it lacks the speed and maneuverability of some of the jets it could face in battle—like the Russian Su-35—so it instead relies on being able to engage or avoid potential opponents before they’re even aware of its stealthy presence.

Using a big, heavy fighter that relies on awareness over speed isn’t a new idea. It can actually be traced back to World War II, when the Allies faced Nazi aerial attacks over London under cover of darkness. Londoners first attempted to counter these bombardments using spotlights and anti-aircraft guns, but soon it became apparent that, in order to win the fight for the skies, the allies would need experienced night-fliers and a plane with a high ceiling, extended loiter times, and the latest in secret tech that would allow them to spot enemy bombers—even in the dark. In response to England’s and America’s requests, Jack Northrop oversaw the development of the P-61, and the allies commenced intensive, all-volunteer, night combat training courses.

The first U.S. Night Fighter squadrons arrived in England in March of 1943, and promptly began exchanging their knowledge of night ops with the Brits, who had already mastered the art to some extent. These men were among the most heavily trained aviators the Allies had to offer, but what they were tasked with doing was something that had never been done before. Little did they know, they’d soon be faced with something no one had ever seen before, either.