Under Threat of Siege

You are a lord in a small castle town on the outskirts of a large European Kingdom. Nearby there are a few villages that are under your laws as well. In each the north, south and west lies other fiefdoms, with lords who swear allegiance to your King. They are your allies, and some of them your good friends. Lord Rockford II of Rockford, sits in the castle to the north, ever since you were granted your position, he has been your greatest ally, and truest friend. The lands to the east are vast, with miles of plains and dense forests, with only small villages, young towns not yet claimed by either country, borderlands with no laws. Reports of a foreign army raiding smaller hamlets have been circulating, and a team of scouts has reported a modestly sized yet well armed army building camp to the east. They haven't shown any threats or acted aggressively as of yet, but they're clearly not here to break bread. You are asleep peacefully next to your wife, whom you love dearly. In the next room over lies your oldest son, asleep with his wife and infant son. He has grown to be a very responsible man and has seen battle more than once. Further down, in the next bedroom lies your second son, the youngest of the two brothers. He has recently reached adulthood but is still young and inexperienced. He is a highly skilled with his sword but has never seen true combat. He is more hot headed than his older brother but still cares for his family and his people. There has been a thunderstorm all night. It still roars but has begun to slow down. You are awoken at night by the commander of your army, along with the Captain of the scouting party who saw the camp. The scout is exhausted and panicked, soaked from the rain and covered in mud. It is clear he rode hard. The Captain tells him to tell you everything...