The field of conflict early warning originated in part from World War II and the lack on the attack of Pearl Harbor. Several coordinated systems for the early detection of a Soviet bomber attack on North America were set up in the early days of the Cold War. The Distant Early Warning Line, or Dew Line, was the most sophisticated of these.
I was recenly revisiting the history of early warning and decided to study the attack on Pearl Harbor in 1941 more closely from the perspective of early warning. Thanks to Google Books, I was able to “leaf” through Clausen and Lee’s Pearl Harbor: Final Judgement, published in 2001. I was surprised to learn that a Naval Reserve Officer, Comdr. William E. G. Taylor, had been assigned to special duties to assist the Army to set up a radar early warning system for Pearl Harbor.
Taylor had previously spent a year with the British Navy and another year with the British Airforce, “during which he had access to and learned the air warning system that helped win the Battle of Britain, both ashore and afloat. In Hawaii, Taylor spent his time trying to “work out the liaison between the aircraft warning systems and the various commands.”
What is striking to learn is that while there we no permanent radar installations, there were “5 mobile sets in use by the Army before the attack on Pearl Harbor” and these, according to Taylor, “were adequate to do a fair job of early warning.” However, the problem was that “the communications between the fighter-director officers’ […], positions, and the fighter aircraft were totally inadequate to control fighters more than five miles offshore.”
Taylor called a meeting on November 24th (note that Pearl Harbor took place on December 7th) in an attempt to get the air warning system operating properly. “Everyone present at the meeting agreed that the interservice operational structure was inadequate; measures needed to be taken immediately to correct the situation.” Minutes of the meeting were circulated to Navy and Army commands the following day.
But as Taylor recounts, “very little was done as a result of this conference. […] We were not able to have either the Army or the Navy agree on an aircraft identification system. We were not able to get men to man the information center. We were able to get no more personnel and the information center remained as it was on 24 November. The fact that the radar stations were shut down, except for 4:00 AM to 7:00 AM made it impossible to continue to train plotters and operators for more than three hours a day, which was not enough. That fact alone did more to slow down the development of the information center than anything else.”
Even if an information center had been fully operational, the absence of trained staff would have made the early warning system ineffective. The system needed both Army and Navy officers to identify which planes belonged to which service, otherwise the center would not be able to distinguish between friendly and enemy aircraft. “As it turned out, the radar station was operating on the morning of December 7, albeit only by operators who were being trained […].”
The trainees actually did pick up the signals of the incoming Japanese planes some one hundred miles offshore. At more or less the same time, however, “a flight of Army B-17 bombers was supposed to be arriving from the West Coast.” But the center had no way of telling whether the planes were American or Japanese since the Army and Navy hadn’t agreed on an identification system.
Note that the Navy did have it’s own radar system which was as effective as the Army’s. But the Navy had actually switched off their radar because the system did not work in port due to the high hills and because the radar interfered with civilian electronic communications onshore. So they switched their equipment off not realizing that the information center wasn’t fully operational.