1941
The British bombing needed to be countered so the Nachtjagd was set up, maybe just before 1941. Initially they were just mostly equipped with Bf-110 Day Fighters (Destroyers). But soon they got better and some Bf110s (Ds I think) were equipped with Spanner Anlage infrared sensors. Those could find any heat source around like all IR sensors

1942
Most of the RAF bombers were obsolete Wellingtons, Whitleys, Albermarles and Blenheims. The Ju88C intruders based at Gilze Rijen went to the Bomber Command airfeilds when the bombers were set to take off and the Ju88Cs would strafe them and (I think) bomb them. Despite the successes Hitler thought the 'terror bombers' should be seen being shot down by civilians and shot down over the cities and the intruder force was sent to the Mediterranean Theatre.
The 1000 bomber raids are mounted. At least one was on Cologne. These devastate cities, particularly Cologne and the Nachtjagd's defences are powerless to stop the majority of bombers coming through and easily devastaing a city. This overwhelms the Himmelbett system! But a raid on Bremen starting on the 25th of June and ending in the early hours of the 26th was the last 1000 bomber raid for a long time. The first was actually a 1046 bomber raid aginst Cologne on the 30th of May ending in the early hours of the 31st. Happy new month tomorrow, Cologne

On the 11th of August the RAF's Pathfinder Force is established to lead the way for RAF raids.
The Rosendaal Halbe homing device was used on Bf110s and employed a very small antenna. It does look quite humble and mouse-like
