Complex sentence: The old war memorial which had been inaugurated on the 4th November 1923, had to be replaced when the town centre underwent major reconstruction, and it was Gouzien who had carried out the sculptural work of the old memorial.
Split into simpler sentences: The old war memorial which had been inaugurated on the 4th November 1923, had to be replaced when the town centre underwent major reconstruction. It was Gouzien who had carried out the sculptural work of the old memorial.