@petekron
You're not separating "person" and "ruler". If a ruler won't sacrifice their children for the good of their people, they are unfit as a ruler and need to be replaced: immediately. Throughout history, princes took to the battlefield as commanders. There were kings who led armies from the front, or directed them from the HQ. There were those who knew they were no good on the field and instead directed logistics from the capitol and decided grand strategy.
Many royals have spilled their blood and lost their heads over the years, all as sacrifices. Ostensibly, some were for the good and proper reason of supporting and defending the people, trying to achieve a better future.
As a mother, a person, sacrificing her daughter is fucking detestable. But a good ruler doesn't have the luxury of being concerned about their personal morality. A leader is a servant, one given power by those they serve to serve them in the best ways that they can. The people want an end to war and they want prosperity? Then the leader must do everything to make that a reality. High-minded ethics and such are for philosophers, not kings. A king without blood on his hands and skeletons under the floorboards is not serving his people in continuities like this - he is giving up countless opportunities and failing his people just to keep himself guilt-free.