of over 5100, and underestimated Soviet troop strength by a million. The historian Lloyd Clark observes that while the Wehrmacht was "feeding on intelligence scraps", the Soviets were "mastering maskirovka". The result was that the Germans attacked Russian forces far stronger than those they were expecting. The commander of the Soviet 1st Tank Army, Mikhail Katukov, remarked that the enemy "did not suspect that our well-camouflaged tanks were waiting for him. As we later learned from prisoners, we had managed to move our tanks forward unnoticed." Katukov's tanks were concealed in defensive emplacements prepared before the battle, with only their turrets above ground level. Glantz records that the German general Friedrich von Mellenthin wrote Operation Bagration, 1944 The 1944 Operation Bagration in Belarus applied the strategic aims and objectives on a grand scale, to deceive the Germans about the scale and objectives of the offensive. The historian Paul Adair commented that "Once the Stavka had decided upon the strategic plan for their 1944 summer offensive [Bagration], they began to consider how the Germans could be deceived about the aims and scale of the offensive... the key to the maskirovka operation was to reinforce the German conviction that operations would continue along this [southern] axis". In particular, the Stavka needed to be certain that the Germans believed the main Soviet attack would be in the south. The Soviet plan successfully kept the German reserves doing nothing south of the Pripyat marshes until the battle to the north in Belorussia had already been decided. Stavka succeeded in concealing the size and position of very large movements of supplies, as well as of forces including seven armies, eleven aviation corps and over 200,000 troop replacements. As for the strategic offensive itself, its location, strength and timing were effectively concealed. Stavka and the Red Army applied the doctrine of military deception at three levels: Strategic (theatre-wide): Stavka hid the location, strength, and timing of the attack, with dummy troop concentrations on the flanks displayed to the enemy before the battle, other offensives timed to work as diversions, and forces left where the enemy expected an attack (three tank armies in Ukraine), away from the true location of the attack (Belarus) Operational: the Red Army hid the locations, strengths and objectives of each force Tactical: each unit hid its concentrations of troops, armour and guns The German Army Group Centre (where the main attack fell)