Panzer divisions were the key element of German success in the blitzkrieg operations of the early years of World War II.

A panzer division was a combined arms formation, having both tanks (German: Panzerkampfwagen, transl.

armored fighting vehicle, usually shortened to "Panzer"), mechanized and motorized infantry, along with artillery, anti-aircraft and other integrated support elements.

[1] By mid-war, though German tanks had often become technically superior to Allied tanks, Allied armored warfare and combined arms doctrines generally caught up with the Germans, and shortages reduced the combat readiness of panzer divisions.

This is similar to a panzer division, but with a higher proportion of infantry and assault guns and fewer tanks.

Since the panzer divisions had the supporting arms included, they could operate independently from other units.

All other units in these formations were fully motorised (trucks, half-tracks, specialized combat vehicles) to match the speed of the tanks.

During the winter of 1941/42, the divisions underwent another reorganisation, with a tank regiment comprising from one to three battalions, depending on location (generally three for Army Group South, one for Army Group Centre, other commands usually two battalions).

Since the Heer and the SS used their own ordinal systems, there were duplicate numbers (i.e. there was both a 9th Panzerdivision and a 9th SS-Panzerdivision).