Oh, right. This thing...
Day 4 - December 15th, 1942
Operation Saturn opens with a massive attack across the entire front north of the Chir salient. In the north, the 6th and 1st Guards Armies launch a concentrated attack on the line held by the Italian 8th Army across the Don. The Axis troops show unexpected resistance and hold for several waves, but after several hours their fortifications are finally rendered untenable by artillery and assault and they break. Soviet troops move up to 10 kilometers into Axis lines, but further advances are stalled by the time wasted on the first attacks. On the right, attempts by the 1st Rifle Division and its supporting Tank Regiments to advance into Boguchan run into the heavily dug in German 525th Infantry Regiment and utterly stall in bloody urban combat.
To the south, three Soviet Armies assault the German positions along the Chir salient on a broad front. The 3rd Guards Army assaults Axis forces apparently consisting of the Romanian II Corps supported by troops from the German XVII Corps and 22nd Panzer Division. After a long bloody battle, the Soviet troops manage to dislodge the defenders from most of their forward positions along the main axis of advance to the south, but fail to advance any more than 5 kilometers.
The 5th Tank Army and 2nd Guards Armies fares better. Faced by little more than the thin line of security troops of Kampfgruppe Spang, Soviet units advances 5 to 10 kilometers along the entire front, inflicting heavy casualties on the Axis troops and capturing their entire defensive line. A large portion of Kampfgruppe Stumpfeld is encircled over the course of the fighting.
No offensive operations are attempted by the Germans, but there are still signs that they are bringing in reinforcements to the southern front, so a recommencement of the offensive in following days is still a possibility. Overall, the first day of Operation Saturn is a mixed success. Heavy casualties are incurred by both sides, and no breakthrough is achieved anywhere yet, but most of the fortified Axis positions have been taken or nullified, so greater advances in following days are likely.