@HDMI1 @Psychronia @karolyn Possibly the German strategy of
blitzkrieg wherein fast troops move at high speed in an attempt to route the opposing forces. In the case of German invasion of France, the French had developed the great french defensive wall acrossed the French Germans border. It's only weak points were through Holland & Belgium, as well as the deep forested area where they did not believe mechanized armored vehicles could traverse. The Germans moved through swiftly with newly developed tanks, crushing their opponents.
Unfortunately, the French did not plans as well as could be expected. Had they, the Germans would have run out of fuel & supplies, making them sitting targets for the French mobile artillery. The problem with blitzkrieg is that you move faster than supplies allow, meaning that if a seige were to take place or a stalemate, the oppsing side could have a tactical advantage through on-hand supplies & other troops.
Typically, this ancient tactic relies upon sending smaller contingents of fast troops (stormtroopers) ahead of one's primary forces in order to blow through unprepared forces, often by surrounding them in a flanking action.
In this case, they surprised the Eastern forces by forming a pincer movement, forcing them to flee. They were setting up for a night seige, only to have been attacked only moments after initiating the orders for [rest]. Notice how the forces have no supply train, no wagons or carts with supplies, only the light rations on their personage. They could only send highly trained knights that are permitted horses (or, who can afford them). Typically, one would ride at a slower pace in order to keep up with supplies.
No, if they used mechanized armored vehicles for transport, they would have likely taken far less time than two days—more likely, they would have reached the forces in under an afternoon, and with heavily weaponized artillery. Remember what the younger brother's forces were gonna get when the MC was at risk of losing hubby to him. Remember all of the mounted artillery inside of mountains, walls, etc., that were gonna blow shit to kingdom come! Just imagine that kind of firepower, but mobile!
Matisa probably would have refused the aid, so he's likely just using the older fast troop transport methods using multiple horses, relay points, or riding & resting with the horses, but not waiting for slower supply trains.