As the Germans made easy progress into Soviet territories during the opening phase of Operation Barbarossa, the Red Army hastily attempted to organize a defensive line to protect the approaches to Moscow. The German attack towards Smolensk began in earnest on 10 July and made good initial progress towards the city. Uneven advances by the different units along the German line and differing levels of Soviet resistance led to the formation of a number of salients. After slowing their advance to regroup and accommodate reinforcements, the Germans were struck by heavy Soviet counterattacks on 21 July, which succeeded in gaining ground in some key areas along the front. The Germans held off the counterattacks and pushed towards Smolensk, trapping some large pockets of Red Army troops. An envelopment formed around the city on 27 July and, following a brief breakout, led to the capture of 300,000 Soviet troops.
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