F. W. Boreham died in 1959, so many of his books are still under copyright worldwide. (UK copyright lasts 70 years from the year of death of the author.) However, most of his books were printed on both sides of the Atlantic, which means that those printed before 1924 are out of copyright for US readers. Some of these are online.
This is perfect for readers who haven’t yet been introduced to Boreham. They should be aware, though, that there’s a difference between his Texts That Made History series and his other books of essays.
Free F. W. Boreham books (PDF) on the Internet Archive (10+)
Free F. W. Boreham audiobooks on LibriVox (5 online and more in progress)
Free F. W. Boreham books on the Online Books Page (10+)
Free F. W. Boreham books on Project Gutenberg (4)