After crossing the Don on 25 July, Army Group A fanned out on a front from the Sea of Azov to Zymlianskaya (today Zymlyansk). The German Seventeenth Army, along with elements of the Eleventh Army and the Romanian Third Army, manoeuvred west towards the east coast of the Black Sea, while the First Panzer Army attacked to the south-east. The Seventeenth Army made a slow advance but the First Panzer Army had freedom of action. On 29 July the Germans cut the last direct railway between central Russia and the Caucasus, causing considerable panic to Stalin and Stavka, which led to the passing of Order No. 227 "Not a step back!". Salsk was captured on 31 July and Stavropol on 5 August. Although the army group made a quick advance, by 3 August the vanguard comprised only light mobile forces and most of the tanks lagged behind, due to lack of fuel and supply breakdowns, despite the efforts of 4th Air Corps, which flew in supplies around the clock.