The Roman army was very well behaved. Well of course. They were paid to be. And they all knew they looked fantastic. Kind of hard not to. The Roman Senate was giving themselves migraines over their image. For the most part they were not young, they were not good looking, and a legislative scroll could hide most of what they were packing.
There were, however, one or two exceptions. Well. One really. Marcus Brutus. (Shut up, Cinna, no one cares what you looked like 20 years ago), And it would be easier to declare Caesar emperor of Rome than it would be to persuade him to strip for a calendar. Every senator did make a valiant effort at it though. They were all, individually, and uniformly, shown the door, or the hall, or the street, depending on their chosen battle ground.
It was Cassius however, who had the winning stratagem. He had something of a stake in it after all. He'd been trying for years to get a glimpse of Brutus 'au naturel'. He wasn't going to miss this perfect opportunity. So, he explained, in very succinctly worded, anonymous memos, that the success of such a calendar was:
"A matter of honour for the whole of the Senate"
that "The winning of this competition with the army was a civic duty"
and "A true Roman would be willing to do whatever it took to insure the honour of Rome and his family."
He then threw these memos in Brutus' window at odd hours of the night, pasted them to his car windows, and almost got caught trying to slip them into his sock drawer. And faster than you can say "Ides of March", Brutus was reconsidering his position and calling the photographer's studio. A date was set for the following Wednesday, calendars were marked, Cassius was roundly congratulated, and Marcus Junius Brutus had a panic attack at 11:20 on the Tuesday before The Grand Day of Nudity and went to seek the help of the only man who could possibly offer him advice on his coming day of travail.
Thus, Marcus Junius Brutus found himself on the front porch of Mark Antony's house on a Tuesday at 11:26 AM.