What is the main conflict in The Mauritius Command by Patrick O'Brian?

Captain Jack Aubrey is appointed Commodore and sent to capture the French-held islands of La Reunion and Mauritius. Using a small fleet and drawing support from the British-held island of Rodriguez, Aubrey sets about reducing the French Indian Ocean fleet. Aubrey's particular friend, Stephen Maturin, assists by making intelligence contacts, distributing anti-French propaganda, and gathering local intelligence. After many months and several setbacks, Aubrey and Maturin are ultimately successful and both islands are captured from the French.