4th Army ( Wehrmacht ) The 4th Army ( ) was a field army of the Wehrmacht during World War II . Invasion of Poland . The 4th Army was activated on 1 August 1939 with General Günther von Kluge in command . It first went into action during the Polish Campaign of September 1939 as part of Army Group North , which was under Field Marshal Feodor von Bock . The 4th Army contained the II Corps and III Corps , each with two infantry divisions , the XIX Corps with two motorized and one panzer divisions , the I Frontier Guard Corps with one infantry division , and two infantry divisions in reserve . It was tasked with capturing the Polish Corridor and thus re - linking mainland Germany with East Prussia . Under Kluge , the Fourth Army completed its task without much difficulty . Part of the Fourth Army attacked south into Pomorze and joined other German forces at Warsaw . Invasion of France . During the attack on the Low Countries and France , the 4th Army , as part of Field Marshal Gerd von Rundstedt ' s Army Group A , went into Belgium from the Rhineland . Along with other German armies , the 4th Army penetrated the Dyle Line and completed the trapping of the Allied forces in France . The then Major - General Erwin Rommel , who was under Kluge , contributed immensely to his victories . Kluge , who had been General of the Artillery , was promoted to Field Marshal along with many others on 19 July 1940 . Invasion of the Soviet Union . The 4th Army took part in Operation Barbarossa in 1941 as part of von Bock ' s Army Group Center . Its initial aim was to trap as many Soviet troops as possible around Minsk . The 4th Army performed well and took part in the capture of Smolensk . However , the poor road network contributed to the stalling of the army group and the 4th Army . On 19 December 1941 , Kluge resigned along with von Bock and Field Marshal Walther von Brauchitsch . Kluge was replaced by General Ludwig Kübler . After the launching of Operation Blue , the 4th Army and the entire Army Group Center did not see much action , as troops were concentrated to the south . However , from 1943 on , as Army Group Center was in full retreat , the Fourth Army also had to move its troops backwards . The Red Army ' s campaign of autumn 1943 , Operation Suvorov ( also known as the " battle of the highways " ) saw the 4th Army pushed back towards Orsha and Vitebsk . Operation Bagration . 1944 saw the 4th Army still holding defensive positions east of Orsha and Mogilev in the Belorussian SSR . The first Soviet summer offensive of that year , Operation Bagration , proved disastrous for the German Armed Forces ( " Wehrmacht " ) , and especially so for the Fourth Army . Commencing on 22 June , an overwhelming Soviet assault saw nearly the entire army trapped in a pocket east of Minsk and destroyed during the first week of July . Very few units were able to escape westwards ; those that did so were involved in desperate attempts to stabilise the German lines for the remainder of the summer , after which the Fourth Army required complete rebuilding . East Prussia . During late 1944 – 45 the 4th Army , now under the command of Friedrich Hoßbach , was tasked with holding the borders of East Prussia . The Soviet East Prussian Offensive , commencing on 13 January , saw the 4th Army driven steadily backwards towards the Baltic coast over a period of two weeks and threatened with encirclement . Hoßbach and Army Group Centre ' s commander , Georg - Hans Reinhardt , attempted to break out of East Prussia ( defying their orders , for which they were relieved of command ) by attacking towards Elbing ; but the attack was driven back , and the 4th Army was again encircled in what became known as the Heiligenbeil pocket . The army held its positions along the coast of the Vistula lagoon until overwhelmed by Soviet attacks in late March . The few remaining forces in the area were incorporated in the East Prussian Army Group commanded by Dietrich von Saucken , which surrendered to the Soviets at the end of the war in May .