Nicely mapped, Gerv. My only point of note would be that I did reduce the distance between the various large cities (retconned it, some might say), so I'd take those riding distances as a gentle day's ride (15 or so miles a day). Excellently done, though.
Your blood is up, and you immediately decide that this aggression will not stand. You check on your men, and find that four of your Halberdiers fell in the conflict, as well as two Archers. You instruct Finn to find enough competent levy Halberdiers to bring the number up to 35, and to prepare to depart downstream after them in a few short hours.
You yell out to gather supplies - lanterns and wool - for fire arrows, and instruct your head Ranger to find enough levy archers to fill out the three longboats and your felucca. You tell them to resupply their arrows, because you are going on the hunt.
Rushing off to the town, you find the scribe, and dictate a rousing letter to Sir Denton and Sir Percival, asking them to join their banners to yours, as the Count has failed to act to this mortal threat to the land. You send the letter with riders, and then tell the Council that their number one priority is to get in the harvest. You tell them to press the refugees into service, and to start getting as much food in as possible.
You return within the hour, and find that you have your 35 Halberdiers, along with around 30 Archers and Rangers milling around the boats. Your felucca has been pulled up, as well. You explain your plan to the gathered men: you will head downstream, aiming to catch them when they camp. When you see campfires, you will put the Halberds ashore with you on lead. The boats will anchor midstream, and then begin firing on the camp. When the boats are aflame, you will charge in and put them to death. The archers will stop firing at a specific battle cry from you.
The men seem to grow in stature as they hear your plan, standing straighter, nodding heads. They will not stand for this aggression. You push off a short while later, and begin slipping downstream. The longboats take a few minutes to get used to, but they are just boats with oars in the end.
***
You put ashore 45 minutes after dark, when you spotted a large series of campfires around a bend. You stand with the Halberdiers, watching flaming arrows streak through the night into the camp. You already see one of the boats aflame. You wait for a few minutes, to let the confusion sink in, and then march forward, giving a specific whoop to warn off the Archers.
The battle is brief and bloody. You caught them unawares, apparently, and a giant block of Halberdiers marching into a chaotic camp is a recipe for a slaughter. They were scrambling for cover from the arrows, and were in various states of inebriation and dishevelment. You personally slay three of the crude men, and the fight is over practically before it begins. All three remaining longboats are on fire. There are no captives, but from what you heard during the din of battle, their language is so different from yours it may not have mattered had you captured one of them.
With the bloody business done, you board boats and begin a slow journey back upriver. Progress is slow, but the men's spirits are high: you took no casualties in the butchery.
***
You arrive in the twilight of the morning to find a small host camped outside of Feroshire. Your pulse races, before you make out Sir Denton and Sir Percival's banner. They ride at the head of around 150 men: 50 light cavalry, the rest a mix of spearmen and bows. You greet them warmly, fighting off exhaustion and the call of your bed to confer with them. What will you plan? What is the next step?