By the summer of 1940, Germany and its allies had conquered most of Europe. The blitzkrieg, or “lightning war,” had proven very effective in overrunning Belgium, Denmark, France, the Netherlands, Norway, and Poland. The early annexation of Austria and Czechoslovakia, added to these most recent conquests, created a “Fortress Europe.”

Great Britain was the only remaining Western European enemy not conquered by Germany.

British forces had been in force in France. Many British planes, tanks, and other heavy equipment had been hurriedly sent to the aid of France, but German military might was too strong. British forces trapped in Dunkirk made a desperate escape in May.

British Prime Minister Winston Churchill, remarking on the defeat of France, said, “The Battle of France is over. I expect that the Battle of Britain is about to begin.”

Churchill said this on June 18, 1940. The German air attacks against Britain began in earnest on July 10.

Most historians agree that the initial intent of the German military was to force a negotiation or surrender. Top German officials estimated that the vaunted Luftwaffe (German air force) would cripple Britain’s defenses within days. Germany had plans for an invasion of Great Britain (known as Operation Sea Lion), but invasion was not at the top of the list. British ships far outnumbered German ships at this point. Some estimates put British fleet totals at eight battleships and 50 destroyers. The German fleet, meanwhile, had been severely damaged in the fight against Norway. If it came to an invasion, the German high command believed, then Germany had to achieve air superiority.

Starting on July 10, 1940, Germany sent wave after wave of fighter planes and bombers to attack military installations in Great Britain. Each day brought renewed attacks, on land and at sea. German bombs targeted airport runways and military installations, including radar stations. German bombs also targeted British ports and convoys and were so successful that the British military ended daytime shipping in the area.

The German attacks were relentless, and they continued day after day. Britain bent but did not break. The longer the British defenses held, the more frustrated German commanders became. What was thought to be a matter of days now seemed a matter of months.

August 13 was “Eagle Day,” a day of intense Luftwaffe activity, with nearly 1,500 aerial attacks on that one day. Losses for the day were 75 German planes and 34 British planes. Similar figures can be found throughout the Battle of Britain.

The aerial attacks continued for months but didn’t give Germany what it wanted. In fact, on September 1, German leader Adolf Hitler decreed that an invasion of Britain was off the table.

Hitler’s decree didn’t stop the bombings, though. They continued until October.

The successful British defense against the Luftwaffe was due mainly to the overall coordination of resources. British pilots, often outnumbered, showed heightened resolve in defending their homeland. The defenses on the ground, led by Air Chief Marshal Sir Hugh Dowding, also benefited from the 51 radar bases that dotted the southeast coast of Britain and from the thousands of members of the Royal Observer Corps (left), who were the eyes and ears of more traditional defense, using low-tech equipment like binoculars to provide information on the German planes’ movements. All of this information was routed through a central communication system, enabling defenders to coordinate their resources and adapt to changing attack patterns.

British pilots who had to abandon their planes could parachute to safety in their homeland and be back in the air relatively soon (assuming that a plane was available). German pilots in the same predicament would be landing in hostile territory and would face capture.

British pilots’ being closer to home also meant that they could stay in the air longer because they needed to fly a shorter distance to reload or refuel, whereas German planes needing fuel or ammunition would have to break off the attack and fly back to the Continent.

As well, the Luftwaffe worked most effectively in tandem with the German ground forces. Tactics that worked well in that capacity didn’t always translate to those needed to conduct successful bombing runs. For example, German bombers had more fuel and could stay in the air longer than German fighter planes, yet fighter planes were needed to help defend bombers, which were primarily offensive weapons.

German military commanders, notably Luftwaffe leader Herman Goering, changed tactics several times throughout the Battle of Britain. At one point, Goering ordered bombing of runways and radar installations. Later, convinced that the radar defenses were of overall unimportance, Goering instructed the pilots to ignore radar stations.

In August, the Luftwaffe began bombing British cities. On the night of August 24, German planes dropped bombs on London. This was an accident. Hitler had prohibited the bombing of London. That didn’t matter to the British military, which bombed Germany’s capital, Berlin, the next evening. In response, Hitler lifted the London prohibition, and the Blitz began.

The last daylight bombing raid by German planes took place on September 30. From October, the targets were population centers.

London and other cities and towns were the targets of German bombs until May 1941. But the shift in strategy away from targeting the ground defense gave that ground defense time to regroup and rebuild. The German bombing of British cities was an attempt to weaken British resolve; but in the end, it was Germany that broke off the attacks. And the revamped Royal Air Force played a major role in the liberation of Western Europe.

Estimates of losses vary widely depending on the source. Both sides inflated the number of enemy planes destroyed and deflated the number of their own planes lost. Reputable estimates of losses of German planes range from 1,600 to 1,800. Reputable estimates of losses of British planes range from 900 to 1,100. In terms of human cost, losses are more accurately numbered as more than 23,000 British dead and more than 32,000 British wounded.

Historians looking backward have viewed the outcome of the Battle of Britain as a turning point in World War II. The result certainly was a major setback for Nazi Germany. Winston Churchill had a more personal and perhaps biased view: “Never in the field of human conflict was so much owed by so many to so few.”