Me-262B-1a/U1 night fighter was developed from a trainer version of Messerschmitt's famous jet. Being a two seater same as the trainer, with second seat positioned in the place of rear fuselage fuel tank, the aircraft had provision for two 300 liter external fuel tanks under forward fuselage in order to increase the range. The aircraft was equiped with "FuG-218 Neptun" long-wavelength radar and "Naxos" centimetric-radar-homing gear, plus armament of two MK-108 30 millimeter cannon and two MG-151 20 millimeter cannon. The type was put through trials in October 1944. The Neptun "antler" antennas slowed the aircraft down, but it was still faster than the hated British Mosquito, which preyed on German night-fighters.
During the following winter, Kurt Welter, head of "Kommando Stamp", used Me-262A-1a day fighters for "Wilde Sau" night fighting, and in April the unit obtained also a few of the Me-262B-1a/U1 night-fighter variants. Despite all the difficulties, Welter claimed 20 kills, making him one of the first jet aces and likely the highest-scoring jet ace in all history.
As the Me 262B-1a/U1 was always considered only a temporary solution, by the end of the war Messerschmitt was working on a prototype of the improved Me-262B-2a night fighter with a longer fuselage and increased fuel capacity. It was fitted with the "Neptun" radar at the outset, but there were plans to fit it with the "Berlin" centimetric radar, with improved range and resolutions and a dish hidden in the nose, instead of the clumsy and drag-inducing "antlers" of the long-wavelength radar. There was also consideration of fitting the Me-262B-2a with upward-firing cannon installed in the rear fuselage to allow it to attack RAF bombers from their belly blind spot. (Source of info: airpages.ru)
Me 262B-1a/U1 W.Nr.111980 'Red 12' was one of the seven aircraft of this type operated by the 10./NJG 11. According to info published in Osprey's book 'German Jet Aces of WW2' it was flown by Leutnant Herbert Altner. Along with other aircraft of this unit 'Red 12' was surendered to the British at Schleswig-Jagel in May 1945 and is shown in the first picture still in its original markings being inspected by RAF officers. After being ferried to Gilze-Rijen, this machine overshot the runway and sustained minor damage. It was probably this incident which resulted in the starboard intake being damaged and replaced with the mismatched example as shown in the second picture. (Source of the pictures: Nachtjäger Vol 2 - Luftwaffe Night Fighter Units 1943-1945.)
The last photo, with a close up of a beautifully restored Me 262B-1a/U1 displayed in a museum in South Africa, shows the typical camouflage of Me 262 night fighters serving with 10./NJG 11.