On 10 July 1940, German attacks on convoys in the English Channel marked the start of the air campaign phase known as the Kanalkampf, or Channel Battle. Historians generally treat this as the beginning of the Battle of Britain. The fighting that followed was not yet the full-scale assault on inland airfields and cities that would come later, but it was an important test of strength, method and endurance for RAF Fighter Command.
Why the Channel mattered
After the fall of France, the Luftwaffe needed to engage and weaken the RAF before any invasion of Britain could be seriously contemplated. Convoys passing through the Channel offered a tempting opening target. They were visible, militarily useful and likely to draw RAF fighters into battle. By attacking shipping, the Germans could combine pressure on Britain’s trade and coastal movement with a deliberate attempt to wear down Fighter Command.
For the RAF, this created an awkward dilemma. Convoys needed protection, but combat over the Channel often favoured the attacker. German formations could strike with bombers and dive-bombers under fighter escort, while British squadrons had to be directed into battle with limited time and fuel. Every interception became a test of the integrated system that Britain had built: radar warning, sector control, ground observers and the rapid commitment of Hurricanes and Spitfires to the right place.
The opening clashes
The actions of 10 July showed the pattern clearly. Channel convoys came under attack, and RAF fighters were scrambled to oppose them. The resulting battles were confused, fast-moving and costly in men and machines. They also revealed that the Luftwaffe could disrupt coastal traffic, while the RAF, though fully engaged, could not protect every ship at every moment.
Even so, the Germans did not achieve a decisive operational breakthrough. Fighter Command continued to respond, to learn, and to preserve the core of its strength. The Kanalkampf was therefore not merely a prelude but a proving ground. British controllers refined interceptions, pilots gained combat experience, and the RAF’s command system demonstrated that it could absorb pressure without collapsing.
Significance in the Battle of Britain
The importance of 10 July lies in what it began. The Battle of Britain did not start with a single enormous raid on London or a dramatic set-piece over Kent. It began with pressure on sea communications, attritional fighting over the Channel and repeated attempts to draw the RAF into battle on unfavourable terms. The Kanalkampf was the opening move in a larger campaign to establish German air superiority.
It also highlighted the relationship between sea power and air power. Convoys were not simply naval targets; they became instruments in an air strategy. Likewise, RAF fighters were not merely defending ships, but defending the wider system by which Britain remained in the war.
A wider air-war reflection
In retrospect, the Channel battles showed both strengths and limits on each side. The Luftwaffe could attack aggressively and impose losses, but it struggled to convert tactical pressure into the destruction of Fighter Command. The RAF, meanwhile, could not prevent every raid, yet it retained cohesion, replaced losses and kept its defensive system functioning.
That is why the opening of the Kanalkampf matters in RAF history. On 10 July 1940, the battle for Britain entered its first sustained phase. The action over the Channel was hard, often overlooked and strategically vital. It set the conditions for the larger struggle that followed and marked the point at which Britain’s air defence system began proving, day after day, that it could survive.