Assassins on defense

[Excist]

Riddle me this:

I had a couple of geared assassins assassinating commanders outside a fort while they chipped at the walls.

When my opponent sent in a test scout they showed up in the battle.

When my opponent stormed again with his main army my assassins hid after the assassination attempt

This was unfortunate since one was an SC and my only real chance at holding the fort.

Anybody know why they would defend the fort in the 1st attack but hide in the 2nd when they were set to assassinate both times?

[Vanguard X]

Just to take a guess- maybe the first attack used the orders you gave them, but after the attack they reverted to scout default order of 'hide'.

[edit]
I thought assassins could only target enemies already in the same province- not enemies moving into a province.