I can’t seem to find any advice on Sieges. The general opinion seems to be use Threat instead. I can see the benefit in Siege were Fortifications / War Machines are involved. So;
When it is worth undertaking a Siege rather than a Threat? What kind of numbers are required for a Siege to work – is it similar to a Threat order? What kind of loyalty is lost each round.
Thanks
Short answer: no one knows.
Longer-yet-not-more helpful answer:
Some parts of siege mechanics are easier to measure than others. War machines, for instance, appear not to do partial damage under sieges. If you have enough to reduce them in a single turn, great, but damage doesn’t accumulate. It’s as if the milita does repairs after the siege.
Loyalty loss from a successful siege also appears to be roughly the same as when a nation loses another pc in combat; I don’t know if it’s the same algorithm, but the result seems similar. That’s probably one of the reasons people avoid it – it isn’t a huge impact, and if it takes so many troops or a great Comm, why not just capture or Threaten?
The rest is more hazy. Is size the main factor? Does Comm skill matter? Do fortifications really dampen loyalty loss? Tough to get isolated data on these, even if players used the order more often.