McGillicuddy feels himself responsible for Lawrence running away.

He said something exasperating to Lawrence, who struck him in a fit of rage, and then ran away." "So my sister-in-law wrote, or rather Miss Fortescue wrote for her." "The army is the place for good hearts," said the Colonel, well knowing what he was talking about.
As Colonel Fortescue spoke, a man was seen, in the fast falling dusk, to pass the window.

The next moment a tap came at the door, and when Colonel Fortescue answered, the door opened and Lawrence walked in.
The Colonel, who had watched Lawrence closely, saw a subtle change in him.

He held his head up, and his face, always handsome, had lost the dissipated, reckless look that dissipated and reckless men readily acquire.

His hair and mustache, which a year before had been coal black, were now quite grey; he seemed another man than he had once been.