Complex sentence: It was the Royal Carabineers Regiment (spanish "carabiñeros reales"), one of the better regiments in the Spanish Army who blocked the narrow road on the edge of a precipice without any chance to go forward or back.
Split into simpler sentences: It was the Royal Carabineers Regiment (spanish "carabiñeros reales"), one of the better regiments in the Spanish Army. Carabineers blocked the narrow road on the edge of a precipice without any chance to go forward or back.