Complex sentence: However military historian Jeremy Black has contended that even though the Jacobite force had become disordered and lost the element of surprise the night attack remained viable, and that if the Jacobites had advanced the conditions would have made British morale vulnerable and disrupted their fire discipline.
Split into simpler sentences: However military historian Jeremy Black has contended that even though the Jacobite force had become disordered and lost the element of surprise the night attack retained a worthwhile prospect of success if it had been pressed on with. Black maintains the assault was abandoned while still practicable and if the Jacobites had advanced the conditions would have made British morale vulnerable and disrupted their fire discipline.