The unit participated in the Battle of Bzura, and carried out raids in the areas of Galicia, Radom, Kielce and Warsaw against rail, airfield and troop targets.

The unit did not participate in Operation Weserübung but instead spent the spring training and resting in preparation for the decisive western offensive in 1940.

From its base at Werl it operated over Belgium and northern France, attacking French armour targets in the Reims and Amiens area.

The Geschwader sank the Royal Navy destroyer HMS Mashona on 28 May 1941, as the British forces withdrew to port.

[4] The Geschwader supported Army Group North's drive into the Baltic states and took part in the Siege of Leningrad.

KG 77 also supported Operation Beowulf, the invasion of the Baltic islands of Osel, Moon and Dago.

During the battle for Estonia it inflicted severe losses on Soviet shipping, with the same dive-bombing tactics used over Norway, France and Britain.

The Kampfgeschwader carried out operations in the Mediterranean and North Africa until June 1943, taking part in the Siege of Malta and the Second Battle of El Alamein.

The unit also resisted the Allied invasion of Sicily, probably destroying the U.S. Liberty ship SS Robert Rowan on 11 July.

I./KG 77 operated from Salon in southern France from March - July 1944, attacking American convoys off the coast of Algeria.