I need to know...

In my city of Bral (which is landbased, there is going to be an
invasion. Scro in about 30 ships (see Ships of the Goblinoids) about 300
troops per vessel) are going to launch an invasion on Bral (Which has 6
ships)? So how long would this attack last? Bral's navy has 6 vessels
and many merchants have vessels as well. Would the Scro (Orcs) attack
more likely be at night? And what if any success would they have against
a town which is essentially a pirate haven? I will be posting this
question to the Spelljammer list too, so sorry to those who will get
this twice. Any help would be appreciated.

JK Wolf