What, exactly, makes a battle decisive?
To start with I looked at what is probably the earliest definitive list I could find of decisive battles, from Fifteen Decisive Battles of the Western World by Edward Creasy, which was first published, I believe in the 1850’s. It is free from Amazon on a Kindle, incidentally, which makes it even more suitable for this task.
Creasy’s list of decisive battles is instructive: Marathon, Syracuse, Arbela, Metaurus, Teutoburger Wald, Chalons, Tours, Hastings, Orleans, the Spanish Armada, Blenheim, Pultova, Saratoga, Valmy and Waterloo.
Now, I suppose that any list of battles claimed to be decisive would be arguable, but perhaps more interesting are Creasy’s reasons for choosing them. Firstly, he claims that it is not the size of the battle, nor the casualties, that make this set decisive. Nor, he suggests are to be considered battles which, although dramatic, had either limited effects (particularly geographically) or ‘merely confirmed’ already noted trends. Thus Plataea is not on his list because the trend noted at Marathon, of Greek military success over the Persians, is, he argues, the decisive one. Hence also the absence of Zama from his list and the presence of Valmy instead of other actions of the Revolutionary Wars.
Now, of course, this is a highly debatable issue. Every statement that Creasy makes could be disputed. I have discussed his ideas so much simply because they give a starting point to trying to understand what we mean as decisive. As I mentioned in a comment at the time, decisiveness seems to work at many levels.
Firstly, I think there is what we might term ‘tactically decisive’ battles. These are the ones with clear cut outcomes on the field. Classically, of course, up to the twentieth century (more or less), a decisive battle would be one where one side was left in control of the battlefield and the other had fled.
In ancient Greece, for example, the victors would put up a trophy, while the defeated would send a herald to ask for a truce while the dead were properly buried. This was an established custom, and serious repercussions could ensue if it was not followed. Of course, in some cases, it was unclear as to who the victor might be, in which case both sides could set up a trophy. But the dead were still buried.
The tactically decisive battle, however, may not actually resolve anything. Marathon, for example, only increased the Persian determination to invade Greece (or so Herodotus reports). It could also be argued that neither Salamis nor Plataea actually achieved anything very much apart from a local defeat of the Persians. Looked at from the perspective of, say, 360 BC, you could argue that the Persians had, in fact, won. This victory would not be a military one, per se, but that, by switching their money from one side to another, they could achieve a balance of power in Greece which gave them access to Greek mercenaries and otherwise kept the fractious cities from being too annoying.
At the next level up we have what I suppose we could term ‘operationally decisive’ battles. By this I mean battles which did, at least, terminate a campaign. An example of this could well be the complex of actions which led to Plataea and Salamis. These battles did, in fact, terminate the Persian invasion of Greece, even if the Greco- Persian wars continued. Another example might be El Alamein, which did at least (more or less) terminate the campaigns in the Western Desert.
At the top level are what I am going to call ‘strategically decisive’ or ‘politically decisive’ battles. These are the big ones, the ones which cause the fall of nations, the transfer of territory and so on. Actually, in that case, there do seem to be relatively few of them. Hasting, probably, is one of them, although I believe that historians can see increasing Norman influence in England significantly before that. Waterloo would be another good candidate, although again, given that Napoleon had already fallen it could be argued that it was simply a post-script to what had gone before. Similarly, while Bosworth was decisive in terms of the switch from Plantagenet to Tudor dynasties, many historians today simply regard it as an aberration, for the “Wars of the Roses” had already finished and the only argument was who, exactly was to be king.
I would imagine that even the categories I have outlined above would be as arguable as Creasy’s criteria for deciding upon which battles were decisive. I suspect that the decisiveness of a battle depends more upon the time frame in which you consider it, and your interests, than by any objective criteria.
If you are interested in the rise and fall of dynasties, for example, then both Hastings and Bosworth are decisive. If you have a broader view history and tend to discount individual events, then, perhaps, Bosworth is a mere hiccough in the development of English monarchy and nation. Perhaps it is only because humanity likes to categorize things extensively that we land up with these sorts of discussions. Ultimately, the answer to the question ‘Was battle X decisive?’ depends on what you mean by ‘decisive’ and at what level you are looking.
So, finally, to the specific example that Chris and I were discussing. Was Solway Firth decisive? Well, obviously, at a tactical level, it was. The Scots were effectively ambushed and trounced by a fairly motley array of English borderers.
At a campaign or operational level, I think that the answer is that Solway probably was decisive, given that the Scots Lords would not cross the border for another go. Whether the demise of James V was a consequence of the defeat is another question which, I suspect, history cannot answer.
Was Solway a strategically decisive battle? Probably not. The Scots and English were still fighting a decade later; neither had been knocked out nor been dealt a decisive blow. In fact, I think that few battles really count at this level of decisiveness.