The codename Circus was given to operations of British Royal Air Force

Royal Air Force

The Royal Air Force is the aerial warfare service branch of the British Armed Forces. Formed on 1 April 1918, it is the oldest independent air force in the world...

 (RAF) during World War II

World War II

World War II, or the Second World War , was a global conflict lasting from 1939 to 1945, involving most of the world's nations—including all of the great powers—eventually forming two opposing military alliances: the Allies and the Axis...

 where bomber

Bomber

A bomber is a military aircraft designed to attack ground and sea targets, by dropping bombs on them, or – in recent years – by launching cruise missiles at them.-Classifications of bombers:...

s, heavily escorted by fighters, were sent over continental Europe to bring enemy fighters into combat. These were usually formations of 20 to 30 bombers escorted by up to 16 squadrons of escort fighters. Bomber formations of this size could not be ignored by the German Luftwaffe

Luftwaffe

Luftwaffe is a generic German term for an air force. It is also the official name for two of the four historic German air forces, the Wehrmacht air arm founded in 1935 and disbanded in 1946; and the current Bundeswehr air arm founded in 1956....

.

At first medium bombers such as the Handley Page Hampden

Handley Page Hampden

The Handley Page HP.52 Hampden was a British twin-engine medium bomber of the Royal Air Force serving in the Second World War. With the Whitley and Wellington, the Hampden bore the brunt of the early bombing war over Europe, taking part in the first night raid on Berlin and the first 1,000-plane...

 were used but even with heavy escort they were too vulnerable to flak and German fighters. They were replaced with Bristol Blenheim

Bristol Blenheim

The Bristol Blenheim was a British light bomber aircraft designed and built by the Bristol Aeroplane Company that was used extensively in the early days of the Second World War. It was adapted as an interim long-range and night fighter, pending the availability of the Beaufighter...

 bombers but they fared no better. Heavy bombers such as the Shorts Stirling were a better fit, but after several missions bomber command needed them back.

The Hurribomber, a fighter-bomber

Fighter-bomber

A fighter-bomber is a fixed-wing aircraft with an intended primary role of light tactical bombing and also incorporating certain performance characteristics of a fighter aircraft. This term, although still used, has less significance since the introduction of rockets and guided missiles into aerial...

 version of the Hawker Hurricane

Hawker Hurricane

The Hawker Hurricane is a British single-seat fighter aircraft that was designed and predominantly built by Hawker Aircraft Ltd for the Royal Air Force...

, was used with better results except that the small bomb load caused little damage.

There were other codenames for similar missions.

• Ramrod - Similar to Circus, but with intention of destroying a target.
• Ranger - Large-formation intrusion over enemy territory with aim of wearing down enemy fighter force.
• Roadstead - Low-level attack on coastal shipping.
• Rhubarb - Small-scale freelance fighter sorties against ground targets of opportunity.