Hyakujitsu no Bara -Maiden Rose-

Two soldiers from warring countries are bound by a pledge as master and servant. Taki Reizen is a commander of sublime beauty, shouldering the fate of his nation. Called "Mad Dog" because of his rough temperament, Klaus von Wolfstadt has sworn his loyalty to him as a knight. Despite this, those around them are cold and disapproving, full of various misgivings. For all their genuine feelings, what will come of love made cruel by the violence of war?

Was discontinued due to its publisher becoming defunct. Has since been picked up by a different publisher and continued in ihr HertZ Magazine in May 2018

Source: Mangaupdates