Article: Battle of Britain
Section: Bomber and Coastal Command contributions

Question: When did the raid on the Channel ports actually happen?

Bomber Command and Coastal Command aircraft flew offensive sorties against targets in Germany and France during the battle.
After the initial disasters of the war, with Vickers Wellington bombers shot down in large numbers attacking Wilhelmshaven and the slaughter of the Fairey Battle squadrons sent to France, it became clear that Bomber Command would have to operate mainly at night to achieve any results without incurring very high losses.
From 15 May 1940, a night time bomber campaign was launched against the German oil industry, communications, and forests/crops, mainly in the Ruhr area.
As the threat mounted, Bomber Command changed targeting priority on 3 June 1940 to attack the German aircraft industry.
On 4 July, the Air Ministry gave Bomber Command orders to attack ports and shipping.
By September, the build-up of invasion barges in the Channel ports had become a top priority target.
On 7 September, the government issued a warning that the invasion could be expected within the next few days and, that night, Bomber Command attacked the Channel ports and supply dumps.
On 13 September, they carried out another large raid on the Channel ports, sinking 80 large barges in the port of Ostend.
84 barges were sunk in Dunkirk after another raid on 17 September and by 19 September, almost 200 barges had been sunk.
The loss of these barges may have contributed to Hitler's decision to postpone Operation "Sea Lion" indefinitely.
The success of these raids was in part because the Germans had few Freya radar stations set up in France, so that air defences of the French harbours were not nearly as good as the air defences over Germany; Bomber Command had directed some 60% of its strength against the Channel ports.
The Bristol Blenheim units also raided German-occupied airfields throughout July to December 1940, both during daylight hours and at night.
Although most of these raids were unproductive, there were some successes; on 1 August, five out of 12 Blenheims sent to attack Haamstede and Evere (Brussels) were able to bomb, destroying or heavily damaging three Bf 109s of II./JG 27 and apparently killing a "Staffelkapitän" identified as a "Hauptmann" Albrecht von Ankum-Frank.
Two other 109s were claimed by Blenheim gunners.
Another successful raid on Haamstede was made by a single Blenheim on 7 August which destroyed one 109 of 4./JG 54, heavily damaged another and caused lighter damage to four more.
There were some missions which produced an almost 100% casualty rate amongst the Blenheims; one such operation was mounted on 13 August 1940 against a "Luftwaffe" airfield near Aalborg in north-eastern Denmark by 12 aircraft of 82 Squadron.
One Blenheim returned early (the pilot was later charged and due to appear before a court martial, but was killed on another operation), the other 11, which reached Denmark, were shot down, five by flak and six by Bf 109s.
Of the 33 crewmen who took part in the attack, 20 were killed and 13 captured.
As well as the bombing operations, Blenheim-equipped units had been formed to carry out long-range strategic reconnaissance missions over Germany and German-occupied territories.
In this role, the Blenheims again proved to be too slow and vulnerable against "Luftwaffe" fighters, and they took constant casualties.
Coastal Command directed its attention towards the protection of British shipping, and the destruction of enemy shipping.
As invasion became more likely, it participated in the strikes on French harbours and airfields, laying mines, and mounting numerous reconnaissance missions over the enemy-held coast.
In all, some 9,180 sorties were flown by bombers from July to October 1940.
Although this was much less than the 80,000 sorties flown by fighters, bomber crews suffered about half the total number of casualties borne by their fighter colleagues.
The bomber contribution was, therefore, much more dangerous on a loss-per-sortie comparison.
Bomber, reconnaissance, and antisubmarine patrol operations continued throughout these months with little respite and none of the publicity accorded to Fighter Command.
In his famous 20 August speech about "The Few", praising Fighter Command, Churchill also made a point of mentioning Bomber Command's contribution, adding that bombers were even then striking back at Germany; this part of the speech is often overlooked, even today.
The Battle of Britain Chapel in Westminster Abbey lists in a Roll of Honour, 718 Bomber Command crew members, and 280 from Coastal Command who were killed between 10 July and 31 October.