Complex sentence: The brigade was ordered to occupy a position on the Aleppo-Alexandretta road and to clear Turkish trenches on the ridge to the west of Aleppo, but when they reached the ridge line on 26 October, the position had been evacuated.
Split into simpler sentences: The brigade was ordered to occupy a position on the Aleppo-Alexandretta road and to clear Turkish trenches on the ridge to the west of Aleppo. However when they reached the ridge line on 26 October the position had been evacuated.