Operation Dragoon
German XIXth Army in retreat - Montelimar trap

Operation Dragoon (initially Operation Anvil) was the code name for the landing operation of the Allied invasion of Provence (Southern France) on 15 August 1944. The operation was initially planned to be executed in conjunction with Operation Overlord, the Allied landing in Normandy, but the lack of available resources led to a cancellation of the second landing. By July 1944 the landing was reconsidered, as the clogged-up ports in Normandy did not have the capacity to adequately supply the Allied forces. Concurrently, the French High Command pushed for a revival of the operation that would include large numbers of French troops. As a result, the operation was finally approved in July to be executed in August.
After the invasion, Allied Force Headquarters praised the Southern France landing as, "a model of effective organization, cooperation of all services and vigor of action — one of the best coordinated efforts in all military history". The beachhead proved to be the largest developed in a three day period during the war.
With the 7th Army front consolidated, General Dahlquist’s 36th Division began a fast-moving effort to counteract any German plans for defense or even an organized withdrawal. Brigadier General Butler was given command of a Division Task Force with orders to advance on Route Napoleon into the Alpine area.
Task Force Butler jumped off from Draguinan and made rapid advance to the north over mountain roads and passes that Napoleon had used on his return from Elba. The T/F reached Sisteron and moved west toward the Rhone Valley. A Task Force under General Stack contacted the Butler T/F and then drove due northward by way of Castellane, Digne and Gap before pressing on to take Grenoble. In one 14 hour period the T/F moved over 90 miles. This northern thrust and envelopment action was intended to cut off German General Johannes Von Blaskowitz’s XIX German Army. Time was critical. Every Division vehicle had to be used day and night in moving equipment, men and supplies. The 36th’s rapid moves enabled it to outdistance much of the German XIX Army, mainly based in the Marseilles-Toulon area.(*)
All 36th Division efforts were placed at destruction of sufficient German forces to necessitate reinforcements being secured from the Normandy area. The Division’s rapid advance did alarm the Germans. A week after landing the Division had moved 250 miles to Grenoble while, in the south, French forces had broken into the ports of Marseilles and Toulon, making the German positions untenable. The German Commander chose the Rhone Valley as his escape route to Germany and began a hasty withdrawal, harassed by the Maqui (French Forces of the Interior - FF1) who were well-coordinated, aggressive French resistance fighters.
On 21 August the 36th Division had elements scattered from Montelimar to Grenoble, Gap, Guilestre, Digne and the beachhead. Fortunately, most of its armor, artillery and combat troops, were in a position to block the German retreat.
The trapped German XIX Army was still a powerful fighting force and as it approached the Montelimar area it began to lash out at the 36th Division. Under threat of enemy armor attack by the German advance force the 443rd Battalion Command Post had to be abandoned the evening of 24 August. It moved from a position 1½ miles southwest of Crest to a position 3 miles south of the town. With intensified ferocity the German forces slammed into the 36th Division’s blocking line, their only escape route to the Belfort Pass into Germany. Meanwhile the 3rd Division had been advancing northwest toward Montelimar, developing a pincers movement on the enemy forces trapped between the 3rd, the 36th and the Rhone River. Although 36th Division units were taking a vicious pounding from German tanks and artillery as they retreated up the Rhone River Valley, the enemy was also absorbing a relentless fire from American artillery. Fire missions for 36th Division artillery jammed radio networks. And U.S. Air Force P-47 dive bombers had destroyed Rhone River bridges, compelling the Germans to remain on the east side of the river on Highway 7. Road blocks set up by U.S. troops were crushed by the overwhelming concentration of enemy troops, weapons and equipment. But U.S artillery continued to destroy escaping vehicles, further blocking the highway escape route. U.S. artillery dispositions enabled accurate fire to be placed continuously on sixteen miles of road, clogged with retreating enemy. In the face of this devastation, enemy armor attempted numerous breakthroughs only to be thrown back.
The German XIXth Army’s huge convoy included about 20 thousand vehicles of all kinds —from heavy cargo trucks to requisitioned French sedans. The U.S. artillery was unmerciful and the carnage at Montelimar was terrible to behold. At least 1000 horses, pulling carts or motor vehicles, had been killed. A few, badly wounded, had to be shot. Some, unharmed, grazed peacefully in the fields after the battle. Smashed, fire-blackened trucks, half-tracks and sedans clogged the highway. Dead enemy soldiers lay among the debris or along the road. Six giant railway guns were captured intact on the railroad paralleling the highway — two were 280 mm and four were 380 mm pieces. Prisoners were taken from seven different divisions as well as many other supporting units. The enemy suffered 7,000 killed or missing, 20,000 wounded, 130,000-140,000 captured and was largely destroyed as a fighting force. In spite of these losses the sheer size of the German XIXth Army in retreat enabled sizeable enemy forces to escape the Montelimar trap, but they were too decimated to be able to set up any kind of a defense until they were behind the Moselle River.

(*) Formed in August 1943 in occupied southern France from Armeegruppe Felber (the LXXXIII. Armeekorps), the 19th Army defended southern France, the Vosges Mountains, Alsace, Baden and southern Württemberg during the Allied invasion of southern France and other large Allied military operations that had as their goal the liberation of southern France and the invasion of southern Germany. Although nominally a field army, the 19th Army was under strength and consisted of third tier soldiers, wounded veterans, conscripts and Hiwis. Southern France in general was treated as a third tier theatre and given minimal attention by the OKW. The entire army was outfitted with damaged and obsolete equipment, with four of the 19th army's divisions designated "static divisions," meaning that they were stripped of all mobile assets and forbidden to move from their assigned positions. The Hiwis in particular proved unreliable and typically deserted or surrendered at the first opportunity. The only asset that posed any threat to Allied plans was the 11th Panzer Division, and even then it had 2 of its five tank battalions reassigned to other formations deemed more critical to the war effort.
[More on the organizational and operational history of the 11th Panzer Division at philonworldwartwo.bl..r-division.html?m=1]