Short answers, pulled from the story.
Case Blue aimed to capture the Soviet oil fields at Baku, Grozny, and Maikop in the Caucasus region. Germany needed the oil to sustain its own war effort and intended to deny these resources to the Soviet Union to collapse the Soviet war economy. Baku alone produced roughly 80 percent of Soviet oil, approximately 24 million tons in 1942.
Case Blue ran from the 28th of June to the 24th of November 1942. The opening attack by Fourth Panzer Army on the 28th of June advanced 48 kilometres in a single day. The Soviet counter-offensive Operation Uranus, launched on the 19th of November, effectively ended Case Blue's momentum and began the encirclement of German Sixth Army at Stalingrad.
Chronic fuel shortages paralysed German armoured columns before they reached Baku, and the sheer distance from Axis supply lines made sustained advance impossible. Baku also lay beyond the range of German fighter aircraft, making bomber raids too costly without escort. Soviet resistance, particularly from Georgian alpine and mountain troops, further slowed the Axis advance after the 28th of August.
Issued on the 23rd of July 1942, Führer Directive No. 45 split Army Group South into Army Groups A and B, ordering both to advance simultaneously in different directions rather than in sequence. This created a dangerous gap between the two groups and pushed already-strained logistics beyond their limit. Commander Kleist later argued that if Fourth Panzer Army had not been redirected under the new directive, Stalingrad could have been taken in July.
On the 19th of June 1942, the Soviets recovered maps detailing the Case Blue plans from the aircraft of Major Joachim Reichel, who was shot down near Kharkov. Stalin dismissed the documents as a German deception, convinced that the real 1942 offensive would target Moscow. As a result, the majority of Red Army troops remained deployed in the north when Case Blue struck in the south.
The Luftwaffe provided critical close air support in the opening phase, at times acting as a spearhead rather than a support force, concentrating up to 100 aircraft on a single Soviet division. The Ju 52 transport fleet flew in 200 tons of fuel per day to keep paralysed armoured units mobile. In October 1942, Fliegerkorps IV launched an air offensive against the Grozny refineries, sending smoke 5,500 m into the air, but the main Baku fields remained out of fighter escort range and were never struck.