Advises to generals of yore have a respected place in many military history books. I could easily name dozen authors who find it irresistibly tempting to suggest certain improvements which were neglected by those who actually fought in the wars instead of spending time in archives and universities. The only problem is that usually such advises would be useless e.g. in Renaissance wars, because these historians tend to miss some minor details which happen to be of paramount importance on the battlefield.
Personally I find it more efficient to assume that everything in Early Modern warfare was applied for a reason unless proved otherwise. Quest for finding such reasons brings into the light far more interesting facts than simple explanation “they were stupid (to use muskets instead of longbows, to charge with lances, to hire mercenaries, etc.)”.
A quick example is in order to highlight what I am talking about. One of the main themes in discussions of the early modern warfare is a matter of battle formations. Usually historians speak about large square formations (called tercios after the term used by the Spanish for their infantry regiments) and thinner, longer formations (called battalions, invention of such battalions is attributed to the Dutch). Peter H. Wilson in his wonderful book about the Thirty Years’ War noted that it has become a historical convention to see battalions as inherently superior to tercios, not least because battalions were associated with higher ratio of firearms to pikes and firearms were considered more progressive. This distinction is not accurate, nor does it correspond to sixteenth-century military thinking.
Frankly speaking mostly this matter is flawed by the fact that there was no such thing as a typical formation in 16th and 17th centuries. Battles were fought in different circumstances and every decent commander chose his formations accordingly. E.g. if your adversary is happy to have lots of heavy cavalry while your cavalry lacks in quantity or quality, it would be logical to form your infantry into big squares instead of small shallow rectangles. Or you could be surprised while on the march, so the march order instantly becomes formation for the battle (that’s why march orders were formed so carefully). So, it is ratios of firearms to pikes were roughly the same in all contemporary armies regardless of formations.
But if Imperial and Spanish generals were nonetheless predisposed to “tercio” formations, there is still a sound reason for that. Like Wilson also notes, the deeper block formations offered better all-round fighting ability than the thinner lines, where each unit relied on its neighbours standing firm or its vulnerable flanks would be exposed if the enemy broke through. The unit in tercio formation assumed a more imposing presence on the battlefield; something that was a considerable advantage as it bore down on a wavering foe. In an age of black powder, the battlefield soon filled with smoke, making it extremely difficult for commanders to see what was happening. It was easier to lose control of long thin lines, composed of smaller, but more numerous battalions, than a deployment of fewer, larger tercios. Tercios and battalions both could be positioned en échelon, or diagonally staggered in chequerboard fashion about 200 metres apart. If tercio became detached or separated, it was generally large enough to fight on alone until rescued. Lone battalion was prone to total destruction.
The officer-to-men ratio remained relatively static after 1590, because of the technical limitations of the available weapons that required them to be used en masse. Around one officer or NCO could supervise about fifteen soldiers, but captains found it hard to command more than three hundred, as the smoke and noise of battle limited their ability to see what was happening and to shout instructions. This was another reason why infantrymen were packed close together in large formations, since it kept them within the sight of their mounted colonel. The flags and drums would be grouped in the centre and used to signal commands to the rest of the unit.
And here we come to the point where we are tempted to give advise to generals of early 17th century: “Ok, we get it. Tercios are good because they are easy to control. But what if you would have more officers and NCO’s to boost control?” But this very clever thought actually crossed minds of military thinkers of the age. In several states there were attempts to create schools for officers and many generals took great care to have the best staff available. The limit was set by money. Weapons of that age dictated certain tactics, and in these tactics advantages of further increase of the number of officers and NCO’s simply didn’t worth the extra florins because officers were very expensive. Sometimes salary of total officer staff in the regiment was close to salary of all common soldiers. More of it, after the war more than half soldiers were disbanded but officers had to be kept permanently because of their uniqueness. Without officers it would take much more time to bring the army to war-time numbers and efficacy. As you see, our initial advise was based on ignoring such boring details of Early Modern finances. Number of officers and NCO’s in armies of early 17th century was inevitable. It was empirically found by 1590 thanks to decades of experiments. Battalions required far more officers than tericos. Difference between tercios and battalions thus depended on subjective measurement of whether the extra numbers of officers and new formations worth more than extra thousands of soldiers. The question was left unanswered by advances in weaponry which led to new tactics.
Command problems also can explain why all armies tried to have more veterans by offering them bonus payment. You needed experienced men and it was reckoned at least a third of your regiment had to be veterans to provide cohesion and sufficient old soldiers to teach new recruits the rudiments of drill and how to survive the rigours of campaign. This need was partially gone only when new weapons and new tactics and new finances made it rational to invest into centralised training of raw soldiers without reducing their total number.
I want to end this short article with expressing my deep impression that evolution of command and control probably was more important side of Early Modern military revolution than evolution of weapons.