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What if something like the Marcks plan was adopted for Barbarossa, which meant the focus was on Moscow and Kiev, with Leningrad a secondary mission, effectively meaning the advance with AG-North would be aimed at support AG-Center rather than racing after Leningrad. So once the Stalin line was breached instead of the 4th Panzer group racing north it instead focuses on supporting AG-Center by moving against the Soviet 22nd army on its flanks and takes Velikiye Luki permanently, rather than the OTL result of 3rd Panzer group diverting a corps north to take it, letting 22nd army escape, then abandoning it and in the process weakening the drive on Smolensk while the Soviets retook the city and formed a problematic flank threat for months.

ITTL then 18th army still pushes up into Estonia on its own, 16th army still moves on Leningrad, but 4th Panzer group then operates on the northern flank of AG-Center in July-September, while there then is no northern diversion of 3rd Panzer group north along with VIII air corps to try and take/cut off Leningrad. So likely 18th and 16th army are stopped well short of Leningrad and don't put it under siege, but the Finns still attack from the North and reach their historical lines north of the city and in the rest of Karelia.

What impact would that have on Barbarossa, specifically the rest of the months of July-September 1941?
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