This theme explores a lesser-known battle of World War I: The Battle of Arras (9th April 1917 – 16th May 1917). Here we aim to provide you with resources to support the exploration of the Battle. These include articles, interactive maps and a resource library linking to materials elsewhere on the web, such as images and digitised artefacts. Many of these items were collected through an innovative, crowdsourcing social media campaign called @Arras95. @Arras95 tweeted the Battle of Arras in real-time, 95 years after the event took place and asked members of the public to join in, and in doing so contribute information and items to the collection. This is available as a Twitter Timeline, a Tweets Map and a Flickr Group.