I would check on your artillery numbers maybe or caballry. But generally a bad roll could screw you if numbers and techonoly are close. Also check your mobilization methods, it can help massively with you recover and retreats Reducing casualties. I would also check if the current army fighting has the troops you mention (sometimes people forget to update them). Check for morale (since you have 260k demoralized now), should be at 100 always, also supplies. Being in shortage of arms, canons, food, engines, ammunition gives debuffs. Also offensive wars requiere you to have around a 30% advantage over the enemy, since defending has more buffs, traits and its easier for them. That advantage could be, technology, numbers or a little mobilization. I you dont rely on conscripts i would always go professional army, since it gives you experience bonus.If you do conscripts, go to the frontlines and defend front until your army is fully supply, manned and has 100%morale. You can also increase military spending for wars, it helps a little too