it was formed in vienna on 1 july 1939, the same day as the 2nd panzer division, but was not assigned to any single military district. commanded by general der panzertruppe heinz guderian, it was stationed in pomerania prior to taking part in the invasion of poland. officially tasked with constructing fortifications in preparation for an attack from polish forces, germany's preparations for the invasion were already well advanced. subordinated within army group north (responsible for poland's north-western danzig corridor region) and supplemented by the 3rd panzer, 2nd infantry, and 20th infantry divisions, xix army corps was tasked to strike southwards towards the vistula river and thereby prevent any eastwards retreat of polish troops to its west. operations began on 1 september 1939, beginning world war ii in europe. during the initial days of the polish campaign, the xix army corps captured the city of pruszcz and a bridgehead east of the river brda, inflicted massive casualties on the polish pomorska cavalry brigade (described by william l. shirer as "sickening evidence of the carnage" and "symbolic of the brief polish campaign"), prevented attempts by the polish 9th infantry division and the czersk operational group to recapture the brda's east bank, been visited at the front by adolf hitler, heinrich himmler, and erwin rommel, and suffered casualties of 150 fatalities and 700 wounded. moved to operating east of the vistula supporting the 3rd army's left flank and following the battle of różan, they were positioned to join in attacking warsaw from the north but were hampered by the slow progress made by army group south. von bock instructed guderian to set his sights onto brest-litvosk, deep in the polish rear though miscommunications with the infantry-based xxi army corps caused casualties and risked them being encircled by polish forces. the battle of brest-litovsk followed soon after, with xix army corps troops slowed but emerging victorious, and guderian ceded the city to the red army after the soviet invasion of poland and in line with the molotov–ribbentrop pact, which his troops had unknowingly violated. xix army corps then represented germany in the subsequent german–soviet military parade in brest-litovsk. the unit received several commendations once the polish campaign ended on 6 october, with guderian himself awarded the knight's cross of the iron cross on 27 october.