From point defense to layered fighter direction

The interwar concept used observers and later radar to summon fighters much as a land-based warning network launched interceptors during the Battle of Britain. Radar first supplemented observer posts and then became the primary warning source, while human observers remained useful for confirmation. Expanding land-based patrol systems could create identification problems, including British formations nearly intercepting one another. At sea, however, the failure to obtain the desired interceptor forced the Royal Navy to rely on patrol aircraft already in the air. Exercises developed for larger strike carriers then became the basis for layered fleet defense, with airborne fighters able to reinforce carriers elsewhere in the formation.