Complex sentence: The 5th Cavalry Division was relieved by the infantry on the morning of 25 September; they "left that place (Haifa) at once" to reach Kefr Kenna about 17:00 on 26 September where they concentrated.
Split into simpler sentences: The 5th Cavalry Division was relieved by the infantry on the morning of 25 September. They subsequently departed Haifa, reaching Kefr Kenna about 17:00 on 26 September where they concentrated.