Over the course of 15 years Andrew Carroll has collected more than 100,000 letters by US soldiers from every war in America's history.

The project began as a personal quest to preserve wartime correspondence and all it reflects about war.

But now Mr Carroll, as director of the Center for American War Letters, is in the final steps of donating his collection to Chapman University in California for safe keeping.

Letters in the collection range from rebukes of British rule during the American Revolution, to the last written words of a soldier in Vietnam just hours before his death.

One of the most striking revelations about the collection, Mr Carroll says, is that each successive generation seems to forget the horrors of previous wars.

Produced by the BBC's Thomas Sparrow and David Botti

Additional images: British Pathé and Getty Images