I recently took the time to read Machiavelli’s “The Art of War,” not to be confused with the much earlier Sun Tzu work. The two have no relation, save the subject. Machiavelli was, if I dare say so, long-winded, but he was a fountain of useful information concerning what was in his time, merely a vision of the future, but which would become the modern army in times to come, based on the old Roman army; and because the old Roman army featured so prominently in his conception, he was very detailed concerning Roman arms as well.
One very small thing which I learned from a different source: the reason the Macedonian phalanx was able to employ both a long spear and a shield was due to the use of counterweights on the butts of the spears. While the force of a single person’s thrust was thus virtually non-existent, the thicket of points facing an enemy in a united advance was very difficult to penetrate effectively. However, the counterweight made the mere act of holding the spear steady relatively easy. The Romans did employ a spear, but, if I recall correctly, only on their rearmost line; Machiavelli explains that there were less men in the second and third lines of a cohort, consecutively diminishing, so that should the first, densely packed line fall, they have somewhere to form up that can (more or less) accommodate their entire number and be immediately stiffened against all attack. Thus, a Roman cohort is like a video game character with three “lives” until it is Game Over.
Machiavelli relates how Julius Caesar and others have destroyed armies allowed to move half their number across a river before attacking, as advised by Sun Tzu, and how deception in war is vital in attack, retreat, and maneuver to the success of the brilliant general. Also, acts of personal generosity and honor by individual leaders did just as much as the force of arms to win over provinces (or “new principalities” in The Prince parlance), even if we can say that such acts were not more important than force of arms, without which such leaders would be merely loved, but not feared as well.
I hope I’ve summarized some of the best parts, because reading that book is a slog, even with a translation into modern English. Still, it’s refreshing to read a work written by someone with such a sharp mind for detail and such zeal for classical warfare.