Its white fury appalled me.

What he had borne hitherto from the Major, God only knows, but this was the last drop in the cup.
Daily insults, ceaseless provocation, even the humiliations of personal violence he had borne with superhuman patience; but this last injury, this wantonly cruel outrage, this deliberate destruction of an amount of thought, and labour, and suffering which only the writer himself could fully estimate--this was intolerable.
What might have happened had the Major been sober and in the possession of ordinary physical strength I hardly care to think.

As it was, his weakness protected him.

Derrick's wrath was speechless; with one look of loathing and contempt at the drunken man, he strode out of the room, caught up his hat, and hurried from the house.
The Major sat chuckling to himself for a minute or two, but soon he grew drowsy, and before long was snoring like a grampus.

The old landlady brought in lunch, saw the state of things pretty quickly, shook her head and commiserated Derrick.