 On 2 July , the southern section of Army Group South – the Romanian 3rd and 4th Armies , alongside the German 11th Army – invaded Soviet Moldavia , which was defended by the Southern Front . Counterattacks by the Front 's 2nd Mechanized Corps and 9th Army were defeated , but on 9 July the Axis advance stalled along the defenses of the Soviet 18th Army between the Prut and Dniester Rivers . 
