Army Group B in the context of "Fall Rot"

The Manstein plan or Case Yellow (German: Fall Gelb; also known after the war as Unternehmen Sichelschnitt a transliteration of the English Operation Sickle Cut), was the war plan of the German armed forces (Wehrmacht) for the Battle of France in 1940. The original invasion plan was an awkward compromise devised by General Franz Halder, the chief of staff of Oberkommando des Heeres (OKH, Army High Command) that satisfied no one. Documents with details of the plan fell into Belgian hands during the Mechelen incident on 10 January 1940 and the plan was revised several times, each giving more emphasis to an attack by Army Group A through the Ardennes, which progressively reduced the offensive by Army Group B through the Low Countries to a diversion.

In the final version of the plan, the main effort of the German invasion was made against the Ardennes, the weakest part of the Allied line, where the defence was left to second-rate French divisions in the Second Army and the Ninth Army, on the assumption that the difficulty of moving masses of men and equipment would give the French plenty of time to send reinforcements if the area was attacked. The Seventh Army, which had been the most powerful part of the French strategic reserve, had been committed to a rush through Belgium to join with the Dutch Army to the north, in the Breda variant of Plan D, the Allied deployment plan.

The Battle of Stalingrad (17 July 1942 – 2 February 1943) was a major battle on the Eastern Front of World War II, beginning when Nazi Germany and its Axis allies attacked and became locked in a protracted struggle with the Soviet Union for control over the Soviet city of Stalingrad (now known as Volgograd) in southern Russia. The battle was characterized by fierce close-quarters combat and direct assaults on civilians in aerial raids; the battle epitomized urban warfare, and it was the single largest and costliest urban battle in military history. It was the bloodiest and fiercest battle of the entirety of World War II—and arguably in all of human history—as both sides suffered tremendous casualties amidst ferocious fighting in and around the city. The battle is commonly regarded as the turning point in the European theatre of World War II, as Germany's Oberkommando der Wehrmacht was forced to withdraw a considerable amount of military forces from other regions to replace losses on the Eastern Front. By the time the hostilities ended, the German 6th Army and 4th Panzer Army had been destroyed and Army Group B was routed. The Soviets' victory at Stalingrad shifted the Eastern Front's balance of power in their favour, while also boosting the morale of the Red Army.

Both sides placed great strategic importance on Stalingrad, for it was one of the largest industrial centres of the Soviet Union and an important transport hub on the Volga River: controlling Stalingrad meant gaining access to the oil fields of the Caucasus and having supreme authority over the Volga River. The city also held significant symbolic importance because it bore the name of Joseph Stalin, the leader of the Soviet Union. As the conflict progressed, Germany's fuel supplies dwindled and thus drove it to focus on moving deeper into Soviet territory and taking the country's oil fields at any cost. The German military first clashed with the Red Army's Stalingrad Front on the distant approaches to Stalingrad on 17 July. On 23 August, the 6th Army and elements of the 4th Panzer Army launched their offensive with support from intensive bombing raids by the Luftwaffe, which reduced much of the city to rubble. The battle soon degenerated into house-to-house fighting, which escalated drastically as both sides continued pouring reinforcements into the city. By mid-November, the Germans, at great cost, had pushed the Soviet defenders back into narrow zones along the Volga's west bank. However, winter set in and conditions became particularly brutal, with temperatures often dropping tens of degrees below freezing. In addition to fierce urban combat, brutal trench warfare was prevalent at Stalingrad.

The 3rd Army (Romanian: Armata a 3-a) was a field army of the Romanian Land Forces active from 1916 to the 1990s. It fought as part of the German Army Group B during World War II, in Ukraine, the Crimea, and the Caucasus. General Petre Dumitrescu commanded the 3rd Army for much of that time.

The 3rd Army contained the only Romanian divisions trained by the Germans, and as a result, it was a significantly better fighting force than the fellow 4th Army during the Battle of Stalingrad.

The Battle of Dunkirk (french: Bataille de Dunkerque) was fought around the French port of Dunkirk (Dunkerque) during the Second World War, between the Allies and Nazi Germany. As the Allies were losing the Battle of France on the Western Front, the Battle of Dunkirk was the defence and evacuation of British and other Allied forces to Britain from 26 May to 4 June 1940.

After the Phoney War, the Battle of France began in earnest on 10 May 1940. To the east, the German Army Group B invaded the Netherlands and advanced westward. In response, the Supreme Allied Commander, French General Maurice Gamelin, initiated "Plan D" and British and French troops entered Belgium to engage the Germans in the Netherlands. French planning for war relied on the Maginot Line fortifications along the German–French border protecting the region of Lorraine but the line did not cover the Belgian border. German forces had already crossed most of the Netherlands before the French forces had arrived. Gamelin instead committed the forces under his command – three mechanized forces, the French First and Seventh Armies and the British Expeditionary Force (BEF) – to the River Dyle. On 14 May, German Army Group A burst through the Ardennes and advanced rapidly westward toward Sedan, turning northward to the English Channel, using Generalfeldmarschall Erich von Manstein's plan Sichelschnitt (under the German strategy Fall Gelb), effectively flanking the Allied forces.

Army Group North (German: Heeresgruppe Nord) was the name of three separate army groups of the Wehrmacht during World War II. Its rear area operations were organized by the Army Group North Rear Area.

The first Army Group North was deployed during the invasion of Poland and subsequently renamed Army Group B. The second Army Group North was created on 22 June 1941 from the former Army Group C and used in the northern sector of the Eastern Front from 1941 to January 1945. By then, this second Army Group North had gotten trapped in the Courland Pocket and was accordingly redesignated Army Group Courland. On the same day, the former Army Group Center, which was now defending the northernmost sector of the contiguous Eastern Front, was renamed Army Group North, assuming the status of the third and final iteration of the army group.

Operation Fischreiher (German for heron) was an extension of Case Blue, part of the German invasion of the Soviet Union in World War II. General Friedrich Paulus' 6th Army, and part of the 4th Panzer Army under General Hermann Hoth, was to advance across the Don river towards the city of Stalingrad on the Western bend of the Volga river.

The original operational plans had called for a defensive line on the Don river by Army Group B, while Army Group A under General List was to advance south towards the oil fields in the Caucasus. The diversion of Operation Fischreiher became an offensive in its own right, to the detriment of the drive south by Army Group A.