Marcellus was enraged, more so than he had ever been in his life. His mother, who had cared for him by her lonesome since he was a small boy, was dead, and he was to blame. Truthfully, he embarked on this journey knowing that the woman was as good as dead, but that did not mean his heart was cold to what had just happened. Honorius had abused his authority as Emperor to arrest the woman for one single purpose, to lure Marcellus out of hiding so that he may claim his head.
Unfortunately, this did not go as planned. Marcellus had resisted the demand to hand himself over. Knowing full well the kind of character a petulant man-child like Honorius had. If he had gone peacefully to Honorius, the man simply would have killed his mother before his very eyes, before having him beheaded. Naturally, he would not give up his life so willingly, and because of this, he had marched an army on Ravenna, abandoning his duty to protect the Empire's borders as he did so.