Operation Bellicose was an attack by Avro Lancaster bombers of the Royal Air Force on a German radar factory housed in the former Zeppelin Works at Friedrichshafen and the Italian naval base at La Spezia. It was the first shuttle bombing raid in the Second World War and the second use of a Master Bomber. In early June 1943, Central Interpretation Unit photo interpreter, Claude Wavell, identified a stack of ribbed baskets at the Zeppelin Works as Würzburg radar reflectors. After Winston Churchill viewed the photos at RAF Medmenham on 14 June, No. 5 Group RAF received the surprise orders on 16 June to attack Friedrichshafen during the next full moon.

On approach to the target, Wing Commander Gomm (467 Squadron RAAF) assumed control of the operation when the aircraft of Group Captain Slee, the master bomber, developed trouble. The main force was ordered to bomb from 4,600 metres (15,000 ft) rather than the planned 3,000 metres (10,000 ft) due to heavy flak. In the first phase, the Pathfinder Force (PFF) and Wing Commander Gomm dropped Target Indicator (TI) bombs for the main force to aim at. In the second phase, as dust and smoke obscured the TIs, Gomm ordered the main force to use 'time-and-distance' bombing runs from a location on the Lake Constance shore, along a measured distance to the target.

The bombers damaged the radar factory and destroyed the unsuspected V-2 rocket production line also housed in the Zeppelin Works, so that Bellicose accidentally became the first Allied air blow against the German V-weapons programme. No Lancasters were lost and from Friedrichshafen, the aircraft continued to the United States Army Air Forces (USAAF) base at Maison Blanche, Algeria. On 23–24 June, eight of the original force of sixty Lancasters remained in Algeria for repairs and the remaining 52 bombed the Italian naval base at La Spezia, damaging an oil depot and an armaments store, then flew to Britain, again without loss.

The Zeppelin shed, 300 m × 50 m (980 ft × 160 ft) and 60 m (200 ft) high, had been built at Friedrichshafen-Löwenthal airfield in 1930–1931 and used by the Zeppelin company's last and largest airships, the LZ 127 Graf Zeppelin, LZ 129 Hindenburg and LZ 130 Graf Zeppelin II. After the Hindenburg was destroyed by fire in New Jersey in 1937 and the two Graf ships were broken up for scrap at Frankfurt in 1940, the vast hangar fell into disuse. In early 1943 it was dismantled and transported in sections on a specially laid track 3 km (1.9 mi) to the industrial suburbs of Friedrichshafen, where it was reconstructed.

British aerial reconnaissance of southern Germany was mainly carried out by de Havilland Mosquito PR IV and PR VIII aircraft of 540 Squadron from RAF Benson, Oxfordshire. The photographs were sent for assessment to the Central Interpretation Unit at Danesfield House near Medmenham, Buckinghamshire, 24 km (15 mi) from Benson. At the beginning of June 1943, Squadron Leader Claude Wavell, head of G Section (Radar & Radio) at Medmenham, noticed stacks of ribbed metalwork lying outside the Zeppelin shed in recent 'covers' of Friedrichshafen. The pattern of the stacks had changed between photographic sorties, implying activity, and Wavell identified the metalwork as parts for the distinctive 7.3-metre (24 ft) lattice reflector dishes of Giant Würzburg radar (Würzburg-Riese) sets.

The appearance and size of Würzburg-Riese dishes had been known to British intelligence since 2 May 1942, when Flight Lieutenant A. E. 'Tony' Hill, in a Spitfire PR IV of 1 Photographic Reconnaissance Unit from Benson, had taken low-level oblique pictures of a German radar station at Domburg on Walcheren Island, Netherlands. The pictures showed two Würzburg-Riese, pointed in different directions, so that the analysts got both a profile and a more full-face view. In the profile shot, a startled Luftwaffe member was standing at the foot of the ladder to the control cabin behind the dish, giving scale to the picture. A previous oblique by Hill, taken on 15 December 1941, had shown an example of the original, much smaller Würzburg set, with a 3-metre (9.8 ft) sheet-metal dish, on a Normandy clifftop. This led to Operation Biting, the Bruneval Raid of 27–28 February 1942, in which C Company of 2nd Battalion, Parachute Regiment under Major (later Major-General) John Frost, parachuted from Armstrong Whitworth Whitley bombers of 51 Squadron (Wing Commander Charles Pickard), stole the Würzburg and brought it to England aboard Motor Gun Boat (MGB) 312 of the Royal Navy.

In radar matters, Medmenham reported to Dr Reginald Victor Jones, Assistant Director of Intelligence (Science) at the Air Ministry. Jones's department, drawing on information from air reconnaissance, PoW interrogations, resistance agents in France and Belgium, Enigma cipher decrypts, and the monitoring of Luftwaffe radio traffic and radar signals by RAF ground stations and specially equipped bombers known as Ferrets, had built up a detailed knowledge of the German air-defence system. The Würzburg-Riese was similar in signal to the original Bruneval Würzburg, operating at 560 MHz, but it was more precise and longer-ranging due to its more powerful transmitter and its much larger reflector dish. By 1943, while the original Würzburg was still in service with flak and searchlight batteries, the Luftwaffe used the Würzburg-Riese for ground-controlled interception, vectoring German night fighters onto British bombers. The Würzburg-Riesen were installed in pairs, as seen in Hill's Walcheren pictures, because one set tracked the bomber while the other tracked the fighter, until the fighter's airborne radar acquired the target.

Jones mentioned the Friedrichshafen findings to Prime Minister Winston Churchill's chief scientific adviser, Lord Cherwell (Professor Frederick Lindemann), in whose Oxford laboratory Jones had once worked as a researcher. According to Wavell, Churchill visited Medmenham, viewed the Friedrichshafen covers, and asked, "Have we been there yet?" Wavell said no; the RAF had not bombed Friedrichshafen. Cherwell had spoken to the Chief of Air Staff, Air Chief Marshal Sir Charles Portal and with the Prime Minister's interest engaged, Operation Bellicose was ordered.