By mid 1942, the German invasion had already cost Russia over six million soldiers, half killed and half captured by the Germans, and a large part of its vast territory and resources. With the help of its arctic winter, it stopped the exhausted Germans just before Moscow and pushed them back a bit. But in the summer of 1942, when Russia was still very weak from its tremendous losses, the German military was again ready to demonstrate its formidable fighting force.
Hitler's Generals wanted to attack in the direction of Moscow again, in order take Russia's capital city, its heart and nerve center, and to crush most of Russia's remaining military forces while doing so, but Hitler now personally commanded the German army, and he listened to his Generals much less than before.
In April 1942, Hitler issued "war directive 41", which detailed his plan for the Russian front for summer 1942, code named Operation Blue. The plan was to concentrate all available forces in the southern flank of the long front, destroy the front line Russian forces there, and then advance in two directions to the primary and secondary objectives, which were the two most important remaining industrial centers in South Russia:
1. Advance far South-East, through the mountainous Caucasus region, to capture the rich oil fields on the Caspian Sea.
2. Advance East, to Stalingrad, a major industrial and transportation center on the West bank of the wide Volga river, the main waterway of inner Russia, that runs all the way from North of Moscow to the Caspian Sea in the South.
It's important to note that Hitler's directive did not demand to occupy the city of Stalingrad. The directive was "to reach Stalingrad itself, or at least to cover it with heavy artillery, so that it will no longer be an industrial or transportation center". The German army achieved this objective with minimal losses in the first day of the battle of Stalingrad. It was the stubborn battle to occupy the city itse...