As the title suggests, the focus of this book is on the works of Caesar, though some thirty pages are devoted to Tacitus' Germania. According to Schulz, Caesar in Gaul initially tried to reform his four thousand-strong Gallic cavalry by integrating Roman officers down to quite a junior level (this rests largely on the decurio, L. Aemilius, mentioned at B Gall 1.23). Nonetheless, they remained unreliable, and after the disasters and vexations of his fifth and sixth years in command Caesar realized — rather late in the day for a ‘great’ general — that the war was not winnable without cavalry superiority. Hence he started to use German cavalry, or rather Doppelkämpfer, since a foot warrior ran and fought alongside each horseman. S. successfully shows that from the seventh campaign onwards they were present as a decisive shock force on numerous occasions. One of the book's most interesting ideas is that Caesar, who claimed for years to be defending Gaul (and Rome) from the German menace, eventually used Germans to conquer Gaul. In the Civil War, the cavalry were decisive in the almost bloodless victory over Afranius in Spain, and so highly did Caesar think of the Doppelkämpfertaktik that before Pharsalus he trained a new force — the Germans having been mostly left behind in Italy — to fight in this way. The African campaign of 49 b.c. is dealt with more from a literary point of view; the comparison drawn between Caesar's depiction of Sabinus' downfall (B Gall 5) and that of Curio (B Civ 2) is detailed and very interesting, though I should hardly have expected to find it under the title Caesar zu Pferde.

This raises a perplexing question: what is the unifying theme or subject matter of this book? It is hard to understand, as far as the historical questions are concerned, why the evidence of the pseudo-Caesarian corpus is so little exploited, especially when the Spanish War is preoccupied with cavalry matters; similarly, for what reason is Hirtius' Gallic War 8 considered, but the Alexandrian War (possibly also written by Hirtius) overlooked?

Some obvious evidence is missed. For example, S. catalogues the thousands of kilometres Caesar journeyed to and fro as governor of Gaul, something which ‘only an excellent rider with great endurance’ could manage (19); yet Suet., Iul. 57, which indeed describes him as a skilful horseman, also tells us he ‘travelled very great distances with incredible speed in a carriage’. Other evidence is over-interpreted. For example, B Gall 5.35 does not mention cavalry (185); similarly, the mixed force of Numidian infantry and cavalry (B Civ 2.25) are taken to be Doppelkämpfer (172 n. 173), whereas the source does not say this, and indeed the number of horse and foot does not match.

Still, there is much of value here. A self-contained ‘equestrian precis’ (262–302), dealing with ancient horsemanship and the most relevant aspects of equine natural history, is appended. One useful insight amongst many is that a relatively high level of remounts (i.e. extra horses beyond the number of troopers) was required in antiquity, because of the lack of iron horseshoes. This factor is often overlooked in the examination of the logistical requirements of ancient armies. Also of great interest are the author's successful experiments, illustrated by photographs, with the mounted use of the spear, which help elucidate certain aspects of the Germania, and the Doppelkämpfertaktik (with S. being pulled along by a galloping horse).