We often joke about the British starting wars badly, but muddling through in the end, do we not. I think that in the period in question this is often a function of the sheer size of the empire and the difficulty of concentrating force across time and space in a sufficiently timely fashion to meet the immediate operational imperative. Thus too few soldiers in a colony or theatre of operations when the balloon goes up. Eventually the proper force level clicks into place, the tide turns and the victory is won.
Organization, training and discipline, (I would also add a 'sense of duty' and a worthy honour code, from both of which so much else flows), is everything...you are right. They were (and still are) surprisingly rare characteristics amongst the world's armies. To paraphrase Voltaire, God is, after all, not on the side of the big battalions, but the best shots.
Dr Mike Snook MBE psc