The Russians knew the German intentions for the Kursk salient. A Russian spy ring, ‘Lucy’, revealed the plan to Stalin as early as 8 April, 1943. General Rokossovsky commanding Central Front issued orders for preparation of defenses south of Orel on 10 April. General Vatutin, commander of Voronezh Front, issued his orders on 12 April. The commanders expected the German assault in the second half of May, after the spring thaw. Marshal Zhukov presented the defensive plans to Stalin on the evening of 12 April, within 24 hours of arriving in Moscow.
Immediately civilians began preparations. Roads and railways in the expected combat area were built, or repaired. Anti-tank trenches eventually totaling 3,100 miles in length were dug. Three to six defensive belts, each with two to three layers were constructed in the areas most likely to be attacked. Defensive works included block houses and anti-tank strongpoints. Evacuated towns were incorporated into the defensive works which were intended to funnel and concentrate enemy armored vehicles into kill zones.
To the east of Kursk a solid line of defense was established to protect the rear areas in case of a German breakthrough. This Reserve Front, soon renamed Steppe Front was commanded by General Koniev. If the German attack was blunted, wearing itself out on the Russian defenses, the Reserve Front had orders for a counter offensive.
By June more than 300,000 civilians were employed to complete the defensive works. In the meantime, partisans and the air force conducted attacks all along the German supply lines. Eventually, these defensive works along the Central and Voronezh Fronts contained 1.3 million men, 19,794 artillery pieces and mortars, and 3,489 tanks and self-propelled guns. They were supported by 2,650 aircraft.
By early July the Russians awaited the German attack with anxious anticipation.
Jack Kruse, Author 