The Hardest Day: Why Britain’s Airfields Became the Target

By GlobeBids History Desk

Published 18 August 2026

On 18 August 1940, Luftwaffe formations attacked British airfields and aviation infrastructure during one of the most intense days of the Battle of Britain. RAF fighter pilots intercepted the raids, but Britain’s response depended equally on radar operators, controllers, telephone staff, ground crews, repair teams and civilians living near the targets.

The anniversary is widely remembered as the Hardest Day. Its importance becomes clearer when the fighting is viewed as a contest between connected systems rather than as a succession of isolated aerial duels.

Key points

• Radar reports became useful after personnel filtered them and controllers directed squadrons
• Ground crews, emergency services and nearby communities carried the burden of repeated attacks
• Aircraft-loss totals vary according to definitions, timing and treatment of damaged machines

Why airfields were central to the German strategy

The Battle of Britain was a struggle for air superiority. Germany needed to weaken the Royal Air Force’s capacity to oppose operations over southern England and the English Channel, while Britain needed to preserve a functioning defensive force.

That made airfields attractive targets. Bombing a runway could interrupt flying, but the more consequential objectives included operations rooms, telephone connections, hangars, workshops, fuel supplies and aircraft on the ground. A sector airfield was especially important because it helped direct other stations within its area.

The Luftwaffe’s information was not always complete, however. British airfields had different functions, and German planners did not consistently distinguish Fighter Command sector stations from satellite, training, bomber or coastal aviation sites. Attacking an airfield therefore did not automatically mean striking a critical point in the fighter-control network.

The Royal Air Force Museum’s account of the Hardest Day describes the operations involving the RAF and Luftwaffe on 18 August. Kenley and Biggin Hill were among the prominent airfield targets associated with the day’s fighting, while attacks also affected aviation facilities elsewhere in southern England.

How the fighting unfolded on 18 August 1940

German raids approached in separate formations and at different heights, forcing RAF Fighter Command to judge which movements represented the greatest danger. Some aircraft acted as escorts, while bombers and dive-bombers were assigned to airfields and other aviation targets.

British squadrons met these formations in a series of interceptions rather than one continuous engagement. Aircraft took off, fought, landed to refuel and rearm, and sometimes returned to action. Controllers had to avoid committing every available squadron to the first detected raid because later formations could be heading towards a different target.

A compressed timeline

• During the morning, warning stations and control rooms tracked German activity across the Channel.
• Successive raids placed pressure on Fighter Command’s ability to identify targets and allocate squadrons.
• Airfields including Kenley and Biggin Hill came under attack during the day’s operations.
• Between raids, personnel treated casualties, repaired damage, restored services and prepared surviving aircraft.
• By evening, both air forces had sustained serious losses and damage, without the British defensive network being eliminated.

The intensity gave the day its later name, but it was not a self-contained contest that decided the campaign before nightfall. Encyclopaedia Britannica’s Battle of Britain history places it within the wider German attempt to gain air superiority in 1940.

The Dowding system connected radar to the squadrons

Britain’s defensive advantage did not come from radar alone. The Dowding system, named for Fighter Command leader Air Chief Marshal Hugh Dowding, connected early warning, observation, communications, command centres and operational airfields.

Chain Home radar stations could detect approaching formations while they were still over the sea. Reports then travelled through a filtering process intended to reconcile overlapping or uncertain plots. Once hostile aircraft crossed the coast, the Royal Observer Corps helped track their direction and strength over land.

Information passed through Fighter Command’s hierarchy to group and sector operations rooms. Controllers used it to order selected squadrons into the air and guide them towards likely interception points. The system conserved pilots, aircraft and fuel by reducing the need for continuous standing patrols.

From warning to interception

The chain depended on several linked actions:

• Radar personnel detected and reported an approaching formation.
• Filter-room staff compared plots and reduced duplication.
• Group controllers assessed the threat and assigned resources.
• Sector controllers ordered squadrons to readiness or take-off.
• Observer reports helped follow formations after they crossed the coast.
• Airfield personnel launched, recovered, refuelled and rearmed the fighters.

No element was infallible. Radar produced estimates rather than perfect pictures, communications could fail, and controllers worked with incomplete information under severe time pressure. Its value came from combining imperfect reports quickly enough to support decisions.

The people who kept damaged stations operating

An airfield remained useful only while people could make it function. Ground crews inspected engines, patched aircraft and loaded ammunition. Armourers, fitters, riggers, drivers and fuel personnel prepared machines for another sortie, often while the operational situation was still changing.

Bomb damage created a second contest on the ground. Repair parties filled craters, cleared debris and restored buildings or services. Telephone engineers worked on communication lines because an intact runway offered limited value if controllers could not receive information or issue orders.

Firefighters, medical staff and Civil Defence personnel responded to fires, casualties and damaged structures. Administrative workers and telephone operators also sustained the flow of information upon which commanders relied. Many of these roles were performed by women serving in organisations including the Women’s Auxiliary Air Force.

Communities near targeted sites were part of the same landscape. Residents faced air-raid warnings, blast damage, disrupted roads and emergency restrictions. Homes, workplaces and public services could be affected when bombs missed military objectives or struck the wider perimeter around an airfield.

Recognising these experiences does not diminish the danger faced by aircrew. It explains how fighters could continue taking off after an attack and why damaging buildings did not necessarily disable an entire sector.

Why aircraft-loss totals require careful attribution

Published totals for the Hardest Day differ. Some historians count aircraft destroyed during combat on 18 August, while others include machines that returned damaged but were later written off. Assessments can also vary over whether non-operational losses, uncertain claims or aircraft repairable at unit level are included.

Contemporary combat claims present another problem. Pilots and anti-aircraft units could report the same aircraft, and fighting at speed made confirmation difficult. Claims recorded immediately after battle should therefore not be treated automatically as verified losses.

A reliable comparison must identify its source and explain whether it uses combat reports, squadron records, maintenance documents or later archival research. Without that methodology, a precise number can imply more certainty than the surviving evidence supports.

The most durable lesson of 18 August 1940 does not depend on selecting one disputed total. The Luftwaffe inflicted substantial damage and forced Fighter Command into demanding engagements, but it did not break the connected warning, control, airfield and repair system. Britain’s defence endured because information and labour continued moving through that network after individual sites had been hit.

Source: Royal Air Force Museum