'Lucky Strike' was an Allied unrealised scheme for General Sir Bernard Montgomery’s Anglo-Canadian 21^st Army Group to strike to the north-east in the direction of the Seine river, where bridges near Rouen were to be taken by Major General R. E. Urquhart’s British 1^st Airborne Division, after the break-out from the Normandy lodgement area of northern France, rather than to the west in the direction of the ports of Brittany, relying on the development of communications with the 'Mulberry' harbour and with Cherbourg until the port of Le Havre could be captured (June/July 1944).

It had previously been decided that the Breton ports of Brest on the province’s north-western tip and St Nazaire on the northern side of the Loire river’s estuary would be essential to the build-up of Allied forces before the decisive eruption into central France could take place. In the event reduced forces were nonetheless allocated to the move into Brittany as Major General Troy H. Middleton’s US VIII Corps (spearheaded by Major General Robert W. Grow’s 6^th Armored Division in the north and Major General Lunsford E. Oliver’s 4^th Armored Division in the south) and Major General Walton H. Walker’s US XX Corps of Lieutenant General George S. Patton’s US 3^rd Army were used to secure Brittany.

The area was garrisoned by General Wilhelm Fahrmbacher’s XXV Corps, which comprised Generalmajor Hans Kroh’s 2^nd Fallschirmjägerdivision in Brest, Generalleutnant Hans Junck’s 265^th Division in Brest and Lorient, parts of Generalleutnant Karl Spang’s 266^th Division in Brest, and parts of Generalleutnant Josef Rauch’s 343^rd Division in Brest.

The XX Corps took Nantes with little difficulty, so sealing off Brittany before it turned to the east to link with the rest of the 3^rd Army, but a harder lot befell the VIII Corps, which took Rennes on 3 September, Vannes on 5 August and Brest on 18 September, but then had to lay siege to Lorient and St Nazaire, which held out against US and later French investment for the rest of the war. The battle for Brest was one of the fiercest battles fought in the aftermath of the 'Cobra' break-out from the Normandy lodgement gained by the Allies in 'Overlord'.

A key element of the Allied plan for the invasion of mainland Europe and the subsequent defeat of the German forces there demanded the capture of major port facilities in order to ensure the speedy delivery of large quantities of matériel and supplies: it had been estimated that 26,000 tons of supplies would have to be delivered each day to nourish the 37 Allied divisions scheduled to be located in France by September 1944. The main port the Allied forces hoped to seize and use was Brest at the western tip of the Brittany peninsula in north-western France.

The initial needs of the invasion forces could be satisfied in the very short term by the pair of large 'Mulberry' artificial harbours which the Allies planned to create on the Normandy, but the seizure of ports on the Atlantic coast of Europe was necessary to ensure longer-term needs, because any shortage of supplies could easily strand the invasion armies and the 'Mulberry' harbours could handle only limited tonnages and were vulnerable to adverse weather, as proved by the destruction of the harbour of Omaha Beach in a gale soon after D-Day.

Suitable ports could be found along the northern coast of France, and particularly the port of Brest in Brittany, for a long time the main French fleet base on the Atlantic coast and the westernmost port in France. The Allied strategists considered even possible that, after its capture, supplies could arrive directly from the USA to Brest, bypassing England and more speedily reaching the Allied armies moving to the east toward Germany. Other ports which could be useful to the Allies were St Malo, Lorient and St Nazaire in Brittany, and Cherbourg and Le Havre in Normandy.

'Sledgehammer' had been considered for the capture of Cherbourg by direct assault, but after the failure of the 'Jubilee' raid of Dieppe in 1942 the Allies opted for beach landings followed by the capture of ports. Appreciating that this might well be the case, however, the Germans had started to build fortifications around these ports earlier in the war, using the forced labour of the Organisation 'Todt', as part of the 'Atlantic Wall' concept. Some of these ports were also major U-boat bases, and great bomb-proof concrete submarine pens had been constructed in them, and these proved themselves essentially invulnerable to Allied bombing.

After the start of 'Overlord', Lieutenant General Omar N. Bradley’s US 1^st Army extended its western end of the Normandy lodgement to the western side of the Cotentin peninsula between Carteret and Portbail, so cutting off the German forces in the northern part of the peninsula. Here Cherbourg fell on 27 June, but the Germans had comprehensively destroyed the port facilities before surrendering.

After 'Cobra', the XX Corps isolated the Brittany peninsula from the rest of German-held France by taking Nantes on the Loire river estuary, and the VIII Corps was allocated the task of capturing Brest and at the same time securing the northern flank of the Allied breakthrough. The German troops trapped in Brittany retreated to the fortified ports of the peninsula as 3^rd Army troops moved in and surrounded them. The heart of the German defence was the so-called Festung 'Brest', whose garrison was commanded by General Hermann-Bernhard Ramcke, a paratroop veteran of the North African campaign. The forces available to him in Brest were the 40,000 or so men of Ramcke’s own 2^nd Fallschirmjägerdivision, Spang’s 266^th Division, Generalleutnant Erwin Rauch’s 343^rd Division and other elements.

The fortress and port city of St Malo, held by Oberst Andreas Maria Karl von Aulock’s Gruppe 'Aulock' based on Generalleutnant Friedrich-August Weinknecht’s 79^th Division, was captured by Major General Robert C. Macon’s US 83^rd Division on 17 August, but its small port facilities had been destroyed by the defenders. A German garrison stationed at nearby Cezèmbre island surrendered, only after days of heavy naval gunfire and powerful air attacks, after disabling its naval guns. It was clear that the Germans were attempting to deny the Allies the use of French ports as long as possible by defending the fortresses built around them and damaging the docks as much as possible.

The leading formation of the VIII Corps had meanwhile reached the outskirts of Brest on 7 August, and the city was soon surrounded by the VIII Corps. The fight proved extremely difficult, for the German garrison was well dug in and included a significant element of high-grade Fallschirmjäger forces. The airborne soldiers lived up to the reputation they had deservedly won in battles such as that at Cassino. While some less capable units surrendered after offering only limited resistance, the paratroop regiments defended their ground well in the face of considerably superior forces, air attacks and US assaults. As a result the attackers suffered heavy losses for every small advance they achieved into the city, despite their use of their heavier artillery firepower and air superiority to overcome the defence rather than attempting a hand-to-hand assault. The Germans had stockpiled considerable quantities of ammunition for the city’s defence, however, and possessed weapons of many calibres (from light Flak weapon to naval guns) emplaced in the fortifications and also in specially constructed pillboxes. The fighting was therefore intense, and house-to-house combat became inevitable.

In the form of the original French and later German constructions, the fortifications proved very difficult to overcome, and heavy artillery was used in an essentially urban scenario by each side. Eventually the old city of Brest was all but razed to the ground, only a few mediaeval stone-built fortifications being left standing. Ramcke surrendered the city on 19 September after destroying the port facilities so comprehensively that they could not be repaired in time to help the war effort in the manner which had been anticipated.

The high cost of taking Brest persuaded the Allies to surround and isolate, rather than attempt to take, the remaining German-occupied ports in France with the exception of those that could be captured straight off the march. The sole exception was Le Havre, which was taken by Lieutenant General Sir Miles Dempsey’s British 2^nd Army on 12 September in 'Astonia'.

Some of the isolated Breton ports surrendered only on 9 May 1945, one day after VE-Day.

The need for ports such as Brest was fully confirmed as the Allied armies pursued the German formations east across France: the former had to operate over steadily lengthening lines of communications as the latter’s own lines were shortening, and by September 1944 the Allies were forced to slow by the inadequacy of their supplies. Cherbourg was the only northern French port that was repaired in time to be of use to the Allies: by 16 July this port was unloading some 2,000 tons per day, a figure which rose to 12,000 tons per day by August. Had it been possible to deliver sufficient supplies through French ports, the Allies might well have been in the position to attack the industrialised western part of Germany before the winter of 1944/45.