From July 14-20 the Front's northern armies successfully penetrated the deep German defenses on the Rava-Ruska and Lviv axes and with all available German reserves committed or already destroyed the Front prepared to expand the offensive on the direction of Drohobych. 1st Guards and 18th Armies had been fighting local actions during this first week in order to pin German forces in place while the reserve 107th Rifle Corps and 4th Guards Tanks had shifted to 38th Army's sector to exploit its breakthrough toward Lvov. On the night of July 19/20 forward elements of the 30th and 74th Rifle Corps conducted a reconnaissance-in-force to determine German dispositions; 20 prisoners were taken and on several sectors the forward defenses were penetrated. In order to exploit these successes the forward detachments of 30th Corps, including those of the 129th Guards, went over to the offensive after noon and soon determined that the German forces had begun to withdraw to the west, covered by strong rearguards.