Killing the watchmen would have been rash and foolish. Besides, you won't get paid for their lives - just Prince Aldun's.
You are near the gatehouse to the castle bridge. The portcullis is down and two men of Prince Aldun's household men-at-arms stand watch.
The portcullis - it's a crude, wooden affair. In Marir there are three portcullises before the keep and each one is made of solid, black iron. Tonight you will put Narvir back in its place.
The rain is little more than a sea fret, rattling lightly off the guards' helmets, but the growing thunder promises a downpour very soon. The men-at-arms are wearing gambesons and shortswords, each has a spear and a household insignia. There will be more men within shouting distance, probably sleeping in the gatehouse until it's their turn to stand guard.
They're coughing and sneezing, complaining about their duties and the coming storm.
"...foreigners get to sit by the fire and drink wine while we're out here in the cold."
"Did you see the bride's father? Never seen a man so fat ahorse."The castle is on an island a short way into the bay. The bridge is the only real means of access unless you can swim.
You came by this way yesterday morning and noticed there is some scaffolding underneath the bridge that you might be able to climb over. After that it's just a matter of choosing a wall to scale with your rope and hook, stealing into the keep, finding the Prince's bedchamber or privy, and... well, the rest should come naturally.