Sacking of Edoras

So, Isengard would be the side with any real forces in the area. Rohan's forces would all be retreating to Helm's Deep. Which is wise as Edoras is not exactly set up to handle a full invasion. Which then raises the question of how many troops Isengard would send.   It seems to me that the forces he sent to sneak across the river for the trap at the Fords would be the forces used in his attacks on Edoras and Dunharrow. That started off with a force of 1,000 to 2,000 Dunlendings, 1,000 to 1500 warg-riders and 2,000 uruks. Now, coming up with exact losses is kinda difficult for this analysis, so I will be borrowing from the books. I will also be using the lower numbers, as the objective of the Rohirrim reinforcements would be to simply break their allies out rather than inflict losses on the other side. Which gives us actually all the uruks, 100 warg riders and 500 wild men.   Which means a total of 500 to 1,500 wild men and 900 to 1,400 warg riders. Some of these would be needed for the Helm's Deep operation. So I'm going to say that 200 wild men and 200 warg riders would be sent to Edoras and Dunharrow. The rest would march with the main army.

So, remember Isengard's rockets? Also, remember the quote from Wellington about their effectiveness against towns? Well, here we go. I think the Wargs in this force would be carrying the rockets. But their batteries are only 178. Which means the attack force would charge to the area and defeat whatever defenses are left as soon as possible. The Wild Men would surround the town and work with the 22 wargs not with rockets.   The attack itself would mainly involve the rocket wargs. Because of the difficulty of shooting from the wargs, they would surround the town and dismount. Then fire into Edoras with incendiary ordinance. This would last 10 minutes based on the British use. Edoras would be left to burn. These troops would then move to rejoin the main army.

But Rohan would not be static either. We have to remember that the mobilization efforts would be ongoing. It would see a slow but steady stream of Rohirrim riding to the area. They would probably arrive too late to stop the burning of Edoras. But all it would take is 2 companies employing a surprise charge as the wargs are still dismounted. Then the light cavalry and fighting retreat tactics could cover the rest of the fighting. Most likely is this entire force from Isengard would be wiped out. But not before Edoras burns.