A new free app for iPhone and iPad offers 30 of the best-known Second World War posters from the Imperial War Museums' (IWM) collection of 20,000. We've collected some of the best below.

The collection includes some of the best-known pieces of 20th century graphic design, as well slogans ingrained in the English language including 'Keep Calm and Carry On' and 'Dig for Victory'. The posters feature striking design, humour, memorable slogans, and above all defiant spirit, which were created to cheer up the citizens of Britain from 1939-45 – or keep them vigilant.

The app allows users to scroll, pinch and zoom (below) to examine each high resolution poster in detail. Users can discover the stories behind the works with information from IWM’s curators.

User can share their favourites on Twitter and Facebook and even order posters directly from the app.