How serious was "giving your word as a gentleman" in the early 1800s? I was just reading a book where the main character lied to the bad guy but gave his word that it was the truth. He believes he did the right thing but is wracked with guilt and is convinced he'll have to give up his naval commission and will be ostracized from polite society. What would really be the ramifications of going back on your word?
For more specifics. The book is Admiral Hornblower in the West Indies -- spoilers ahead if you care. This is set shortly after the Napoleonic wars and Horatio Hornblower (Admiral in His Britannic Majesty's Royal Navy) uncovers a plot to rescue Napoleon from his exile in St, Helena. He caught the enemy ship off of Tobago but didn't have the manpower to take her. Instead he goes to parley with the Napoleon sympathizers and convinces them that Napoleon has died on St. Helena by giving his word. He convinces them that if they continue, they'll start an international incident over nothing and would certainly be hanged once either England or Bourbon France catches up with them. The sympathizers destroy their weapons and sail off to France. Hornblower believes once they get back to France his ruse will be discovered, England and France may be able to stop the sympathizers from sailing again to rescue Napoleon but Hornblower's honor is destroyed. At the end he finds out that Napoleon did in fact die, retroactively making his lie a truth and he exhales a huge sigh of relief.
Not exactly what you asked, but you may find this to be of interest as it deals with the importance of the concept of honor, and specifically this follow-up. It isn't exactly about 'their word' as it focuses on duelling, but both are underpinned by the same concepts of honor and how it defined them as a gentleman.