Paradoxically, there is a strong homoerotic - very common in ancient lit - set of tropes and aesthetics around all this. In contrast, "Serve and protect" is also a part of, familial for example, masculinity, eg, buddies, work groups, etc.
And the romans also had the symbolism of the clenched fist on the military equipment meant to be a metaphor for the phallus. When the came to a town they would try to capture the most fierce warrior, then impale him as if to validate the phallus symbolism. But to say that the Romans were outstandingly brutal or prone to sexual violence is a bit of a stretch. The Romans differed in that they used the imagry of sexual violence to get competitors to submit or flee great distances. When the Romans extended themselves in Northern Gallia, the Gauls, many of them, fled across the English Channel thinking that once the romans weakened, they could come back. And that was the case later some gauls returned, but As Ceaser pointed out they were defeated even if they didn't know it. Rome had a much more difficult time against the germanics, by this time the germanic tribes had learned the tactics of the romans and instead of fleeing or trying to defend a fixed position they learned how to drawn the army out were they could catch it in small pieces.
