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WWII On This Day: April 6

What happened on April 6 during World War II? This date brings together 9 events from 1941 and 1945, with period photographs and links to the full operations documented across WW2 Theatres.

1941
The Soviet-Yugoslav Treaty of Friendship and Non-Aggression dated 5 April 1941; original held by the Archive of Foreign Policy of the Russian Federation.
The Soviet-Yugoslav Treaty of Friendship and Non-Aggression dated 5 April 1941; original held by the Archive of Foreign Policy of the Russian Federation. Archive of Foreign Policy of the Russian Federation, F. 3a — Yugoslavia, D. 10 · official document, public domain Source
Invasion of Yugoslavia, April 1941

The Soviet-Yugoslav friendship treaty is completed in Moscow

During the night of 5–6 April, Yugoslav and Soviet representatives completed a Treaty of Friendship and Non-Aggression in Moscow. The instrument was dated 5 April and expressed Soviet political support for Yugoslav independence. Belgrade had sought stronger material and security support as the German threat became unmistakable. The agreement stopped short of a military alliance, and negotiations over supplies could not alter the immediate balance around Yugoslavia. German forces were already in their attack positions. Within hours, the invasion and the air offensive began, leaving the treaty with diplomatic significance…

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A reconnaissance detachment of the German 5th Panzer Division entering Athens on 27 April 1941.
Bundesarchiv Bild 146-1979-123-32 · CC BY-SA 3.0 DE · Source
German Invasion of Greece, April 1941

Germany opens Operation Marita against Greece

At 05:15 German artillery and aircraft opened the attack against Greek positions along the Bulgarian frontier. XVIII Mountain Corps struck the Metaxas Line while XXX Corps attacked farther east and German mobile forces simultaneously advanced into southern Yugoslavia. The opening plan separated tactical and operational tasks. Mountain and infantry formations were to force or contain the fortified frontier; 2nd Panzer Division and XL Panzer Corps were to exploit Yugoslav routes that could bring German armour behind the Greek line and toward Salonika and Florina. The first hours therefore did not…

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A German Panzer IV of the 11th Panzer Division advancing into Yugoslavia in April 1941.
Bundesarchiv Bild 101I-770-0280-20 · CC BY-SA 3.0 DE · Source
Invasion of Yugoslavia, April 1941

German forces cross into southern Yugoslavia

Before dawn on 6 April, German forces of XL Panzer Corps attacked from Bulgaria across the southeastern frontier. The 9th Panzer Division pushed toward Kumanovo and Skopje while the 73rd Infantry Division advanced toward Štip; another German thrust moved through the Strumica valley toward the Greek frontier. The southern operation aimed to seize Macedonia’s communications centres, break Yugoslav formations before they could complete concentration, and cut the Belgrade–Salonika route linking Yugoslavia with the Allied position in Greece. Mountain roads, demolitions and local resistance slowed individual columns, especially on the approaches…

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German paratroops descending over Crete, May 1941.
Bundesarchiv Bild 141-0864 · CC BY-SA 3.0 DE · Source
The Balkans and Crete

Operation Punishment

Belgrade was bombed for three days without a declaration of war, in an operation Hitler had named Strafgericht, punishment. Estimates of the dead range from about 2,270 to over 5,000, and the National Library with its medieval manuscripts was destroyed. The city had been declared an open city. The raid was explicitly a reprisal for the coup rather than a military operation.

German Invasion of Greece, April 1941

The Metaxas forts hold the direct approaches

Greek garrisons at Roupel and the other Metaxas forts fought from concrete positions, underground galleries and prepared field works against artillery, dive bombing, engineers and infantry. The Hellenic Army records twenty-one autonomous forts within the system. The terrain amplified their resistance. German troops could penetrate between positions and seize exposed ground, yet several forts remained capable of fighting after the wider operational situation had moved beyond them. Ammunition, communication and the ability to reach the rear of the system mattered more with each day. By 9 April German armour approaching…

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German bombing of Belgrade on 6 April 1941.
German bombing of Belgrade on 6 April 1941. Historical Archive of Negotin / unknown photographer · CC BY-SA 4.0 Source
Invasion of Yugoslavia, April 1941

The Luftwaffe begins bombing Belgrade

At about 06:30 on 6 April, Luftwaffe formations began the first major attack on Belgrade. Bombers and dive bombers struck government and military sites, railway and communications infrastructure and extensive civilian areas while Yugoslav air defence attempted to intercept them. The air offensive supported a wider command objective: disrupt the capital as the centre of government and high command while ground forces opened several invasion axes. Telephone, telegraph and transport disruption complicated communication between the Supreme Command and armies whose mobilisation was still incomplete. German attacks on Belgrade continued over…

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Invasion of Yugoslavia, April 1941

Yugoslav fighters contest the opening raids

Royal Yugoslav Air Force fighters rose against the German formations over Belgrade and nearby airfields on the opening morning. Units operated IK-3s, Bf 109Es and Hurricanes, meeting an attacker with greater numbers, a coordinated air plan and the initiative over the Yugoslav air-base network. The Yugoslav pilots sought to break up bomber formations and protect the capital while air units elsewhere tried to preserve aircraft and strike Axis targets. Combat in the air was accompanied by attacks on airfields, dispersal areas and communications on the ground. Losses, damaged bases and…

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Invasion of Yugoslavia, April 1941

German units seize crossings and passes in the northwest

German frontier and infantry units crossed at selected points from Austria on 6 April, securing or probing routes, bridges and mountain positions ahead of Second Army’s main mobile offensive. These operations tested Yugoslav border resistance and protected the German concentration areas while major formations continued moving into position. Local Yugoslav units faced the problem of holding a long frontier without knowing where the principal northern weight would fall. The early crossings remained secondary to the southeastern breakthrough. Their significance grew as Yugoslav command cohesion weakened and Second Army prepared to…

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1945
Men of the 95th Division, US Ninth Army, patrolling Soest after its capture, 7 April 1945.
Men of the 95th Division patrolling Soest, 7 April 1945 · US Army Signal Corps SC 336817 · NARA · Public domain · Source
The Ruhr Pocket

Ridgway's corps joins the attack

XVIII Airborne Corps began its northward advance one day after III Corps. Its formations included the 8th and 78th Infantry Divisions and later the newly arrived 13th Armored Division. The converging attack now involved the equivalent of four corps while the main Allied armies continued east towards the Elbe.

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