Raid on Umbar

Lets say for our purposes that this occurs after the Blue Wizards had been active for awhile. Which should mean a decent amount of preparation for a slave revolt. Lets also say that Aragorn brings some of his Rangers from the North with him, the foundations of the Grey Company. This was around 30 men. Ecthelion II would likely also be willing to send some of Gondor's Rangers to the battle as well. Say 20, the largest group that the Rangers would be used to fighting in. It would also be wise to send some of the elven advisers too. They too are organized with 30 soldiers in their platoon level formations. So the full attack would be 80 soldiers total. Which results in a small force, but one that would be at the high end of training, motivation, discipline, loyalty and special forces specialization.

This leaves us with a likely night attack on the port facilities. Here is the thing. Ships like this from what I remember were stored in complexes similar to warehouses lined along the banks. So should the Rangers be able to get in, it would be a relatively simple matter to burn the buildings. A single fire like this would destroy a lot of the ships, making it easier to wipe out the entire great ship portion of the fleet. This would naturally be the first target. Whatever other facilities they could reach would be next. But once that first fire gets going, their time would be limited. The response would be swift and brutal. At this point the attackers would have to choose between a hasty retreat or face catastrophic losses.   One of the key things motivating a hasty retreat is the arrival of the Ring Wraith. He probably would not have the time or ability to get out his fell beast. They are particularly ill suited for fighting a small number of enemies hiding in a burning urban environment. Plus, it would be unwise to show your full hand at this stage. So the Wraith would primarily move on foot or horse. Still, he would be a powerful force that the raiders would be ill equipped to handle. The more time they spend dealing with him is time the rest of the Corsair fighters would be able to use to cut off their escape. Aragorn would know this. So the second that first scream from the Wraith pierces the night, a retreat would be called.

But the damage would have been done. The main port would be heavily damaged. The facilities alone would probably take long time to replace, not to mention the ships. Then there is the unfortunate slaves there taking care of the ships and all the goods ready for export. But this is the small stuff. Fires are not that easy to put out with medieval technology. So the fires would probably burn for days, possibly expanding to destroy a decent amount of the city.   Naturally, this would demand a decent amount of Corsair resources to contain and rebuild. The Southern Fiefs and the Gondorian central authorities both would probably be less inclined to pay ransom money after. Exports would drop to zero at least for a short period. No raids would be going out until the situation in Umbar is under control.

But this again is secondary. The sight of Umbar burning would be a powerful signal to slaves that now would be their opening. Practically, the diversion of troops would compound this. So now would be the time for the Blue Wizards to make themselves felt. The slaves would rise up. Thus, we can expect a non trivial number of plantation equipment, buildings, manor houses and long ships to be knocked out. Plus, a non trivial amount of slaves would escape. This would probably easily and brutally be shut down by the Corsairs, their Haradrim allies and orcs sent as reinforcements from Mordor. Then both Umbar and Harad have Wraiths stationed there able to control the situation. But the crisis for the Corsairs would worsen dramatically. This would cripple their economy and military power further.