When I play wargames I regularly read books on the subject, view movies, and do some background research. For Dark Summer only the first few turns are well covered by the many publications on D-Day. One interesting source I came across recently is the Imperial War Museum’s website with several articles on D-Day and Normandy. The German Response to D-Day, What Happened After D-Day, and Tactics and the Cost of Victory in Normandy are but a few such articles that will give you more insight into this campaign.
Another book I read some time ago and that I much recommend is If You Survive (George Wilson) written from the perspective of a junior infantry officer that took part from the Saint-Lô breakthrough July 1944 to the assault on the Siegfriedlinie February 1945.
June 13th to June 20th 1944
Turn 2: Allied ground forces are now firmly established on the Normandy coast. The British 21st Army Group mounts several attacks on German positions but makes no progress. The American 12th Army Group advances along the coast towards CHERBOURG and west of BAYEUX. US 29th Infantry Division advances into the swampy area east of CARENTAN linking up with the 4th Infantry Division. But the GE 6th Fallschirmjäger-Regiment and units from 243rd Infantry Division still hold CARENTAN with its bridges and the north-south road connection effectively denying the link up of the Utah and Omaha bridge-heads. The German Heeresgruppe B mounts a limited local counter attack with 17th SS-Panzergrenadier-Division north of SAINT-LO but mainy consolidates the defensive line. The weather remains “Showers” much supporting the German force build up. During “Shower”-Turns the Germans may use the road bonus.
June 21th to June 28th 1944
Turn 3: Sunny weather supports the Allied build up of forces on the Normandy coast. One of the main impacts is the massive appearance of Allied Tactical Air Support. The US receive 3 additional Tac Air Markers to use each combat round! The American 12th Army Group on the right flank advances to the outskirts of CHERBOURG with 83rd Infantry Division in the lead. In the centre the 4th and 29th Infantry Divisions gain CARENTAN and fight their way into the bocage area. The left wing sees heavy fighting at BALLEROY.
The British 21st Army Group mounts several prepared offensives all along the front. At TILLY-SUR-SEULLES and at the bridge-head across the Orne River the British make some progress. All together the Allies are far more aggressive this turn in bearing in mind their now steadily flowing reinforcements and replacements. Allied special forces and airborne formations are disengaged and returned to their bases in England. They render Victory Points to the Germans, if they are destroyed or are still on the map end of turn 5.
The Germans stubbornly defend their thin line. Despite the heavily impaired movement due to Allied air interdiction more and more formations enter the battle. Especially the Kampfgruppen from several SS Panzerdivisions substantially bolster the defenders’ fighting power. Any large scale attack is out of the question, so the intention is to add depth to the defensive line at those areas most vulnerable to Allied attacks.
June 29th to July 6th 1944
Turn 4: The weather stays sunny in this period. So the Allies enjoy full mobilty while hampering the German’s through their air interdiction. The American 12th Army Group aggressively attacks German forces south of CHERBOURG and takes VALOGNES. An offensive by 3rd Armored Division flanked by the 4th and 29th Infantry Divisions pushes back German forces towards PÉRIERS. This has opened a 15km wide gab in the German defences on the COTENTIN. On the right US flank fighting around BALLEROY continues with minor territorial gains. Most importantly US 1st Infantry Division causes heavy casualties on the GE 3rd Fallschirmjäger Division.
The British 21st Army Group mounts several offensives all along its front. It succeedes in expanding the bridge-head over the Orne River east of CAEN while several attacks on CAEN by the 2nd Canadian Corps fail. All together both opposing forces suffer heavy casualties. Most notably the British 53rd Infantry Division destroys a Kampfgruppe of the 12th SS-Panzer-Division. Depending on weather conditions the Allies gain up to 6 steps of replacement versus the German’s 2 steps maximum. Therefore the Allies can much more afford to lose steps then the Germans can.
German OB West can no langer fully contain the Allied invasion force in its beach-heads. The decision is to give up the COTENTIN and concentrate forces to prevent an early breakthrough of American forces towards AVRANCHES or – even worse – a British breakthrough to LISIEUX.