All Soviet histories depicted 'Uran' as the main operation in the initial phase of the 1942/43 series of winter offensives, and most seemed content to suggest, by implication, that it was the only offensive. However, another major undertaking being prepared in October 1942 was 'Mars' (i) which, according to the two sentences devoted to it in the History of World War II, was 'to destroy the enemy in the regions of Rzhev and Novo Sokolniki'. In the area of Rzhev, the object was apparently to finish the effort, started during the summer, against Generaloberst Heinrich-Gottfried von Vietinghoff-Scheel’s 9^th Army. As Novo Sokolniki was already practically in the front line on the western perimeter of the Toropets bulge and, by itself, a point of only modest tactical consequence, the aim there was most probably to strike deep to the south-west into the area behind Generalfeldmarschall Günther von Kluge’s Heeresgruppe 'Mitte'.

Moreover, since the Rzhev area was well-known to General Georgi K. Zhukov, the deputy command-in-chief of the Soviet armed forces, who had already advocated concentration against Heeresgruppe 'Mitte', it seemed likely that it was Zhukov who was as instrumental in creating 'Mars' (i) as in the development of 'Uran'. On 16 November 1942 Zhukov left General Polkovnik Aleksandr M. Vasilevsky, the chief of the general staff, in charge of operations at Stalingrad and went to General Polkovnik Maksim A. Purkayev’s Kalinin Front and General Polkovnik Ivan S. Konev’s West Front to supervise the final preparations for 'Mars' (i), which was scheduled to begin about one week after 'Uran'.

It is almost certain that 'Mars' (i) was at the time seen as considerably more important than was suggested by later Soviet accounts. 'Mars' (i) was planned for implementation in the area that, during 1941 and 1942, had consistently been regarded in Soviet thinking as the most important strategic direction, the one in which Soviet forces had already undertaken a successful winter offensive and in which they could expect to be able to stage a successor on better terms than the first. 'Uran', on the other hand, was a highly speculative venture. The earlier History of the Great Patriotic War came close to stating this in its assertion that the Stavka assumed that the Germans, despite their desperate efforts, would not have achieved their goals, that their offensive would have failed but, yet, neither would they have succeeded in going over to the defensive along the entire Stalingrad sector nor changed the operational deployment of their forces. In Stalingrad, major German forces would still have continued to attack.

Understated as they were, these were enormous assumptions. To expect that Generaloberst Friedrich Paulus’s 6^th Army would somehow not have managed to take Stalingrad at some time between the middle of September and the middle of November was a great deal. To anticipate that the Germans, with the memory of their failure before Moscow still only a matter of months old, would continue a faltering offensive into the winter was still more so. Furthermore, if the Germans did both, it then became necessary to assume that they would also not know how to extricate themselves from a Soviet encirclement undertaking.

'Uran' was essentially a gamble but, when considered objectively, 'Mars' (i) had considerably better prospects, and the Soviet deployment in the middle of November suggests strongly that the Stavka also took this view. On the 620 miles (1000 km) of front between Kholm and Bolkhov, which was the sector held by Heeresgruppe 'Mitte', the Soviets had amassed 1.89 million men, 24,682 pieces of artillery and mortars, 3,375 tanks, and 1,170 aircraft. On the slightly less than 500 miles (800 km) of front between Novaya Kalitva to Astrakhan, which was the sector held by Generalfeldmarschall Maximilian Reichsfreiherr von Weichs’s Heeresgruppe 'B', the Soviets had amassed 1.103 million men, 15,501 pieces of artillery pieces and mortars, 1,463 tanks, and 928 aircraft. Thus the sector between Kholm and Bolkhov, representing 17% of the total front between Lake Ladoga and the Caucasus, had 31.4% of the troops, 32% of the artillery and mortars, 45% of the tanks, and 38% of the aircraft, while the sector between Novaya Kalitva and Astrakhan, representing 14% of the total front, had 18.4% of the men, 20.1% of the artillery and mortars, 19.9% of the tanks, and 30.6% of the aircraft.

If the doubts circling over its prospects resolved themselves favourably, however, 'Uran' did have one significant advantage over 'Mars' (i) inasmuch as the forces allocated to it had a substantially greater numerical advantage over those of the Germans. The History of World War II maintains that the 1.1 million Soviet troops deployed in the sector between Novaya Kalitva and Astrakhan were opposed by 1 million German and Romanian troops, resulting a a Soviet numerical advantage of only 1.1/1. The overall strength of the 6^th Army, Generaloberst Herman Hoth’s 4^th Panzerarmee and General de armatâ Petre Dumitrescu’s Romanian 3^rd Army was in fact far fewer than 1 million men and in all probability just slightly more than 500,000 men, which made the Soviet advantage 2/1. The ratio in the sector of Heeresgruppe 'Mitte' was 1.9/1, using a German strength estimate of 1.0115 million men for the army group in September 1942.

While the ratios varied by only 0.1%, the difference in the composition and capabilities of the forces they represented was considerable, however. The formations of Heeresgruppe 'Mitte' were all German. Of the total for the three armies in the area in which 'Uran' was to be fought, some 250,000 men (almost 50% of the total) were Romanian troops.

It is worth noting that one notable Soviet account represents 'Mars' (i) not as an operation in its own right but rather as a deception undertaking incorporated into the overall deception scheme for 'Uran'. This account states that in the course of the Soviet preparations for the counter-offensive at Stalingrad, the Soviet high command ordered the forces of the Kalinin Front and West Front to manoeuvre as though for an offensive toward the west against Heeresgruppe 'Mitte' with the object of creating the impression that operations for a winter offensive were being prepared there, and not away to the the south-east, and that the deception generated a useful result. Were this the case, 'Mars' (i) would have repaid the Germans nicely for their own 'Kreml' in the previous spring, but 'Kreml' was a deception of the purest type and 'Mars' (i) was not.

It is more probably that 'Mars' (i) was connected to 'Uran' not as an element in the latter’s maskirovka (masking) deception effort, but as a possible way to keep the battle for Stalingrad going until the time was ripe for 'Uran'. According to the History of World War II, 'Mars' (i) was ready for commitment as early as 23 October, and the start order would have been given at any time after this should the Germans have begun taking troops from Heeresgruppe 'Mitte' to reinforce the attack into Stalingrad.

What the Soviet planners did, therefore, was to compromise 'Mars' (i) in order to preserve the conditions deemed essential for 'Uran'. In doing so, the Soviets befuddled the Germans just as effectively as they might have done had 'Mars' (i) been a deception that in fact yielded 'positive results'.

A factor which the Soviets had not adequately considered was not so much the numbers of the opposition, but that his opposition comprised only German troops, as noted above, under the command of one of the German army’s rising stars, Generaloberst Walter Model. As a general commander the XLI Panzerkorps before Moscow in the winter of 1941/42, Model had proved himself particularly adept in defensive operations, and as a result in January 1942 he had been elevated to command of the 9^th Army holding the Rzhev salient, in the process leapfrogging at least 15 more senior commanders just within Heeresgruppe 'Mitte'.

Just before his January 1942 departure to the 9^th Army, Model had held lengthy consultations with both Adolf Hitler and Generaloberst Franz Halder, the chief of the Oberkommando des Heeres’s general staff, who both told Model in unequivocal terms that the would have to be extremely firm in order to save the 9^th Army. When Model assumed command of the 9^th Army, its sector was in a shambles: the Kalinin Front had broken through the German line and was threatening the railway line linking Moscow and Smolensk, which was the primary line of supply for Heeresgruppe 'Mitte'. Despite the danger, Model quickly appreciated that the Soviet attackers were themselves now in a precarious position and immediately counterattacked, cutting off the Soviet 39^th Army. In the ferocious battles that followed, he repelled multiple Soviet attempts to relieve their trapped soldiers, the last being in February. He then squeezed out the pocket in a series of operations culminating in the middle of July after he had been forced into a temporary relinquishment of his command to recuperate.

After restoring the 9^th Army's front, Model set about holding it. His defensive doctrine, which combined conventional thinking with his own tactical innovations, was based on a number of principles: timely intelligence, based on front-line sources and reconnaissance rather than rear-area analysis; a continuous front line, no matter how thinly held; the establishment of tactical reserves to halt any imminent breakthrough; centralised artillery command and control; and the creation of multiple static defence lines designed to slow an opponent’s advance.

Since the end of World War I, the artillery of German divisions had been divided among the divisions' component regiments, which made it difficult to bring the maximum weight of fire to bear on any one point. Model reorganised his artillery into special battalions under the direct control of the divisional and corps commanders.

Multiple static defence lines had, in fact, been prohibited by Hitler on the grounds that the troops would be tempted to abandon their current line in favour of falling back to the next; Model ignored this order.

Using these tactics, Model was able to defend his front successfully throughout 1942 and well into 1943 despite the fact that he was compelled on occasion to lose men and vehicles for the battles farther to the south.

'Mars' (i) was undertaken in the west by Zhukov’s West Front and in the east by Konev’s Kalinin Front under the co-ordination of Zhukov, and from west to east round the perimeter of the German bulge involved the 33^rd, 5^th, 29^th, 20^th, 31^st, 30^th, 39^th, 22^nd and 41^st Armies supported by other formations. The offensive’s primary objective was the destruction of the German salient around Rzhev through the launch of several co-ordinated thrusts by formations of the Kalinin Front from the north-west, north and north-east of the northward-facing German salient with the task of destroying General Karl Hilpert’s XXIII Corps and General Walter Weiss’s XXVII Corps, and taking the areas round Rzhev, Olenino, Bely, Zubstov and Sychevka. After this destruction of the northern part of the 9^th Army, commanded once again from 1 December by Model after his recovery from wounds suffered in May, the Soviet forces were to regroup and link with General Leytenant Yakov T. Cherevichenko’s 5^th Army and General Leytenant Vasili N. Gordov’s 33^rd Army of the West Front, which were to attack in 'Yupiter' (i) some two to three weeks after 'Mars' (i), along the highway linking Moscow and Vyaz’ma. When the German resistance around Vyaz’ma had been broken, Major General Aleksandr A. Shamshin’s IX Tank Corps, Major General Vasili G. Burkov’s X Tank Corps and General Leytenant Pavel S. Rybalko’s 3^rd Tank Army would then penetrate deeper into the rear of Heeresgruppe 'Mitte'.

'Mars' (i) could call on an initial 703,000 men and 1,720 tanks, with 415,000 men and 1,265 tanks earmarked for the subsidiary 'Yupiter' (i) (about 150,000 men and several hundred tanks were used to reinforce the unsuccessful 'Mars' ), while the Germans had about 350,000 men and 1,615 tanks in three combined-arms corps (Hilpert’s XXIII Corps, Weiss’s XXVII Corps and General Maximilian Fretter-Pico’s XXX Corps with 13 infantry and two airborne divisions), and two Panzer corps (General Hans-Jürgen von Arnim’s [from 1 December General Robert Martinek’s] XXXIX Panzerkorps and Generalleutnant Hans-Karl von Esebeck’s XLI Panzerkorps with five panzer divisions and three motorised divisions).