I recently completed the twenty and a half novels of the Master and Commander series by Patrick O’Brian. (O’Brian died before completing the last.) A pastor’s daughter recommended them and after a few pages, I got hooked. The stories revolve around two primary characters in the service of the British Royal Navy during the Napoleonic wars.
These books are ripe with period atmosphere. I can’t stress enough the hi-resolution picture O’Brian gives us of life in the early nineteenth century. While we “text” each other on iPhones about the oil spill in the Gulf, it’s refreshing to explore sophisticated technology lost in the past. And rich technical detail from the period is intricately described—woven into the plot so as to be essential to the story.
The series has been hailed as the some of the greatest historical fiction ever produced. O’Brian comments that his battle scenes are taken directly from actual accounts and that he couldn’t improve upon the real thing. He interjected his own characters into the action and wrapped it all up into a compelling story of their lives.
A major motion picture came out, combining elements from the series. I restrained myself from watching it until I’d completed several of the novels. It did not disappoint.
The books are written with certain glaring eccentricities in style, but even those somehow work to create the illusion that they were written at the time of the action. They take place in the early 1800s, just prior to the time of my own novel.
The Gamemaker's Father 
I read quite a few of those. Excellent. Rather an unusual style of writing, but thoroughly engaging.
I read the Horatio Hornblower books way back when. Are these any different?
Yes they are for a number of reasons. Besides the stylistic contrast, the historical details are more accurate. O’Brian is said to have had access to documents that had not previously been available.