John Churchill is and should be regarded as the great British military commander, yes better than Nelson. He is the greatest military commander of the 1700's. He used technology and geography to his advantage like nobody before him. He crushed the French. Why isn't he regarded more highly within Britain?
Military historians know the Duke of Marlborough and acknowledge his achievements.
What about Cromwell? He had no military experience until the Civil War, and by it's end he had subjugated Scotland, started the conquest of Ireland, and crushed the royalist armies. The battles of Preston, Dunbar and Worcester all show the skill that he had in leading armies.