Go home.

You calmly think about the situation. Yes, you have 50 of your finest guard just outside the Arch Duke's castle. That being said, if by some chance the Arch Duke manages to gather and coordinate his small army, he can bring more than twice that number to the fight. That is a risk you are not willing to take. You call down to the herald, "Tell the Arch Duke of this land that his rightful king has witnessed his treason but will handle it on a later date."

He calmly calls back, "If that is what you wish." Before allowing you to leave the castle and the arch Duke domain with no resistance.

Your Nobility is an uproar over the Arch Duke's action by the time you got back to your capital; even the commoners had given up their infighting and are united against the Arch Duke.

The calls for war are deafening. That is not an exaggeration. As you passed by the town on your way to the castle, men were assembled by the street side to show their support while ladies called out from the windows calling upon justice for you and the former queen. The people were fighting about your action of making the former queen your concubine; now they are quarrelling about who is the more valorous in going to war to reclaim the former queen and the king's unborn child.

Even your royal meeting chambers were not safe from the shouting. Instead of competing who can shirk away their responsibilities and pay the tax the least, your Nobility are trying to upstage each other by providing the most troop with the best equipment the fastest.

There are brags such as “My friend, by the time you bring that amount of troops, my troops are already drunk from the victory celebration”, “My footmen eats your cavalry for breakfast” and “Your mother can lead your army better than you,”

Finally, you have enough and shouted, “SILENCE!”

That single command **** the room into silence. You then say, "I am in agreement with you all we must wage war. But pointless grandstanding without genuine effort is like a lonely man with only his hand to accompany himself; he’s just screwing himself. I don’t need wankers. I want people with a real idea, a real tactic, a real strategy. Otherwise, don’t bother speaking and make yourself look like an ass.”

Your challenge is accepted by Sir Trindon, a headstrong noble who believes every problem can be solved by war, and might make right. " Sire, No matter what these other nobles attempt to blow hot air, when it comes to true military ****, it is my opinion that the Kingdom of Frankia's forces matches our nearly man-to-man. If we wish to preserve our might for future conflicts, I suggest we attack the Lothelsabourg this coming winter when the mountain passes in Frankia are rendered unpassable. Thus, they cannot fully bring their forces to bear against us."

His comment is a good reason why the previous king kept him in confidence. Just like you need a vicious guard dog to take care of a flock of sheep, you need a warmonger like him to control the noisy but docile Nobles in a trading nation such as yours.

Sir Dietrich laughs. "Now, Sir Trindon, I don't know about any future wars, but I am impressed that you use your brain instead of your brawn for once. I second your suggestion."

It is rare for Sir Trindon and Sir Dietrich to agree on anything. For them to agree on something, it must be something you must take into account in your decision. So, you decide. "If no one has any objection, we’ll march in a month after the first snowfalls."

It take thirty-five days for the first snowfall, and the following day you march with your troops to Lothelsabourg. Winter wars are always risky. That same reasoning is why the Kingdom doesn’t consider the possibility of you mobilizing during winter. By the time it realizes your plan, it’s already too late. The mountain passes are already frozen over, leaving Lothelsabourg sparsely defended with just more than a hundred trained soldiers and just as many militias. Their numbers is a mere fraction of what you brought.

Prince Louis, the heir to the Kingdom of Frankia and the fiancee to the Arch Duke's daughter rides out to meet you outside Lothelsabourg gates. Surprised that the Arch Duke is not present, you ask, "So where is the traitorous Duke that **** this war on our two great nations?"

Prince Louis’s expression is grim as he replies "My future father in-law went back to our capital to iron out his reintegration into our glorious land."

Sir Trindon laughs. "So the coward starts a war, and then run to escape the fight."

Prince Louis's face twists in anger "You call him a coward... How dare you call him a coward when you bring your forces bare when you know your enemy cannot? But enough of that, I came here to bring your King the good news. Due to her state, Lady Beatrix cannot travel with the Arch Duke. Thus, she stayed and gave birth to your child yesterday."

Sir Dietrich "Then hand it over, so we can properly care for it."

Prince Louis "I think not, at least not yet. I will return it unharmed before our battle in spring. If you fight before then, his blood will coat our armor."

Sir Trindon screams, "You coward, you hide behind a child."

Prince Louis calmly says, "And you hide behind trickery. So who is the coward?" He then starts to walk away while saying, "You have my terms."

You consider your option.

You can fight them right now, but you risk your son being killed. On the plus side, you will ensure the battle will be swift. If you’re in the mood to show mercy, you can take Prince Louse as a hostage and then trade him for the Arch Duke’s head and his daughter. If you’re in the mood, that is. Choosing this option will cement your position as a king with a firm determination and not to be trifled with.

The second one, will be to return home. When you return to fight in the spring, your army will face a stronger opposition and may lose a lot of men. But doing should ensure your son’s safety, and may prove a popular decision with the commoners.