At the centenary of 2014, 'Blood Swept Lands and Seas of Red' became the surprising star of commemorative activity. This art installation of 888,246 comprised ceramic poppies, planted in undulating waves in the Tower of London moat. Its popularity showed that far from declining, World War I (WWI) commemoration was still intensely popular with the British public. 'Lest we forget' is an innovative project which will use new methodologies to probe a unique and large data set which was collected as part of the installation, and thus to investigate how people made sense of, and engaged with, it. The project will contextualize the installation by explaining the ways in which the public(s) commemorated the First World War more widely, building on a century of WWI historiography and looking at commemoration in a 21st century context. Finally, it will look at whether any other project could achieve public impact comparable to that of 'Blood Swept Lands', and if so, how this might be achieved. Each of the 888,246 ceramic poppies in the installation was created to represent a single life; or rather a death. The number of ceramic poppies and the scale of the installation were its defining features both in terms of the spectacle it created in the moat, but also in the meanings people made of the artwork. Volunteers, staff, visitors and purchasers frequently referred to the emotional significance of 'one poppy, one life'. Each handmade poppy embodied individuality within the conformity which is associated with military service in WWI. No two poppies were the same, connecting the individuality of the dead combatants with the horrifying scale of the war. This project looks beyond the spectacle of 'Blood Swept Lands'. It uses the installation as a case study through which some of the wider issues of WWI commemoration can be understood. It will look at how the public made sense of the WWI centenary, and how they used the installation to create meanings, express emotions, and share these with a wider group of people. It will then explore the ways in which people interacted with 'Blood Swept Lands' through different media; from volunteering to 'plant' poppies, visiting the installation, sharing photographs on social media, and depositing home-made artefacts at the Tower; to attending a nightly roll-call ceremony, or buying a ceramic poppy. The public engaged with the installation on multiple levels, and the levels of public involvement also helped shape the installation and its project, which became a media phenomenon. This research project will investigate the importance of this engagement; it will also critique the way the project was perceived as a 'success' by the public, media and Historic Royal Palaces. It will achieve this by using data collected as part of the Blood Swept Lands project, and applying methodologies from other disciplines to probably the largest data set of commemorative activity available for research. It is timely to study the impact of 'Blood Swept Lands' and its place within WWI centenary commemorations as the 2014-18 centenary draws to a close in 2018. Further fieldwork in 2018 will look at the longer term impact of the 2014 commemorations, and ask whether and how attitudes to 'Blood Swept Lands' and commemoration have changed over the 4 years, 2014-18. The research will explore what constituted the 'success' of 'Blood Swept Lands' and whether this success can be replicated in future commemorations and commemorative programmes. 'Lest we forget' will disseminate its research findings through conference papers and published journal articles. It will bring together heritage practitioners and academics from history, heritage, and memory studies in order to share and discuss future engagement with commemoration in heritage and museums. It will deliver public impact through regular blog posts, public talks and a Teacher Fellowship programme, resulting in 10 new free teacher resources.