In 1941 Grewenig relocated to Plauen when he was recruited to take charge at . Vomag was a manufacturer of industrial sewing machines which had reacted to the decline in Plauen's textile business thirty years earlier by diversifying into trucks and buses. By 1941 it had switched to war production, becoming a major supplier of tanks to the military. Grewenig was mandated to improve efficiencies and expand production. The end of the war in May 1945, found what was left of Germany divided into four occupation zones. Plauen had been heavily bombed, leaving it, according to one source, one of the most completely destroyed towns in Germany. The town found itself on the southern edge of the Soviet occupation zone (after October 1949 the &lt;a href="German%20Democratic%20Republic"&gt;German Democratic Republic / East Germany&lt;/a&gt;). The Vomag plant had been approximately 40% destroyed by bombing, but by February 1946 was nevertheless ready for a return to truck production on a limited scale. At this point, however, the military administration ordered the remains of the factory to be disassembled, crated up and shipped to the Soviet Union as part of a reparations package that had, at least in principal, been agreed between the victorious powers before the end of the war. Sources indicate that Grewenig remained in charge at the Vomag plant till 1947. That year he crossed the (at this stage still completely porous) border separating the Soviet occupation zone from Bavaria, which had ended up in the US occupation zone (after May 1949 the &lt;a href="German%20Federal%20Republic"&gt;German Federal Republic / West Germany)&lt;/a&gt;.