Chapter 18 opens with both the crew and the mutineers racing toward the stockade. After a skirmish that leaves one dead on either side of the conflict, Captain Smollett and the crew occupy the log-house (the main building in the stockade). The captain proceeds to empty his pockets of several things he grabbed from aboard the ship, including the British colours, or, flag.
The captain then sets a tree against the corner of the log-house and climbs onto the roof in order to raise the colours. Doctor Livesey, who narrates the chapter, comments "This seemed mightily to relieve him." Shortly after, the captain uses a second flag to cover the corpse of Tom, the sailor who was killed by the mutineers. These two actions serve to illustrate how much the flag means to Captain Smollett.
Thus, when the squire suggests lowering the flag to make it more difficult for the mutineers to shoot at the log-house, Captain Smollett responds: "Strike my colours! No, sir, not I!" The doctor then states that he and the other crew members felt that the captain's words inspired them and showed their contempt for the mutineers and their attack.