By internal chronology, A Ship of the Line, which follows The Happy Return, is the seventh book in the series (counting the unfinished Hornblower and the Crisis).

Throughout, Hornblower is torn between his love for Lady Barbara and his sense of duty and loyalty to his frumpy wife, Maria.

Since he has been forced to sail with an understrength crew, and had to make do with "lubbers, sheepstealers, and bigamists", he breaks Admiralty regulations and presses twenty sailors from each Indiaman just before they part company.

When Hornblower encounters a squadron of four French ships of the line that have broken through the English blockade of Toulon, he attacks them despite the odds of four to one, and manages to disable or heavily damage all of them.

However, with many of his crew killed or wounded, including Bush, who loses a leg, and his ship dismasted, he is then forced to strike his colours and surrender.