65,329 subscribers a community for 3 years, 5 monthslast post today [+]
All submissions must deal with things that happened exactly 100 years ago, using the Gregorian calendar. August 5, 2014 is all about August 5, 1914.
Start the title of your submission with the relevant date in brackets: [August 5, 1915], for example. If you want to discuss the subreddit itself use [Meta].
How can you participate? Search for and post interesting articles from 100 years ago today. You don't have to do it everyday, but each submission helps us learn what was happening a century ago.
Chronicling America: U.S. National Archives newspaper archive
The Gazette: Official public record of the United Kingdom
How to research: The U.K. National Archives' guide to searching newspaper archives
BBC Radio: 1914: Day by Day
Years ago, /u/DanyalEscaped planned to research World War I day by day from 2014 to 2018, exactly 100 years after the events had happened. He realized that using a subreddit might be easier.
In the first week of August 2013, he started this subreddit in hopes that it would have a big and active community by July 2014, the centenary of the war's beginning. The plan worked, and now it is a thriving community, with more than 60,000 subscribers and daily headlines posted from archives around the world.
Multiverse of anniversary subreddits