HaBO: She Served as Head of Her Father’s Army

This HaBO comes from Diksha, who wants to find this historical-ish romance:

It’s an English novel.

It’s a historical romance (but could also be called fantasy — I don’t remember the exact setting, but it had kings ruling kingdoms and fighting, so maybe medieval).

The heroine was originally supposed to marry the hero’s brother, but he had already gone into a secret marriage, so she is now forced by circumstance to marry the hero instead.

Why is she marrying the hero? Her father doesn’t have a son, so they need a male who can take over the kingdom.

Why is the hero marrying her? His brother already has a claim to their paternal kingdom, so he needs a new kingdom of his own.

The heroine’s father had always been abusive toward her and was also a terrible ruler. Because of that, the heroine had to act as the head of her father’s army — but now the hero bans her from being on the battlefield, which makes her angry.

The hero now has to convince the general public and the army of the FMC’s kingdom that he is a good ruler. They’re very skeptical of him because of their loyalty to the previous king’s lineage, and since the hero carries a different surname, they don’t see him as their rightful king.

The hero also has a backstory involving betrayal: his former lover turned out to be an agent of an enemy kingdom and caused a major attack on his homeland. Because of that, he swore he would never fall in love again.

There’s an enemy kingdom that has long-standing issues with the hero’s kingdom. Later, they join forces with the heroine’s father, and the hero is almost killed — but the heroine pretends she supports the enemy kingdom and ends up saving him.

Another detail: the heroine almost dies later but survives, and she eventually gives birth to a child. The hero decides to give their child her surname.

Very curious about this one because I think I want to read it!