Complex sentence: By troops in the original front line near St. Pierre Divion had bombed southwards and recovered some of the captured front line and the advance up the Hansa Line had reached the north face of the redoubt and then been repulsed during an attempt rush the redoubt.
Split into simpler sentences: By troops in the original front line near St. Pierre Divion, had bombed southwards and recovered some of the captured front line. The advance up the Hansa Line had reached the north face of the redoubt and then been repulsed, during an attempt rush the redoubt.