With World War I as its backdrop, Sam Mendes’ 1917 is one of the most visually immersive films to come out of Hollywood. The movie won three Oscars at the 92nd Academy Awards. But did you know, for its historical accuracy, the film relied significantly on a Canadian university?

In the opening scene of the film, actor Colin Firth is seen poring over a trench map while giving a bunker briefing. That map, which depicts a network of trenches in Northern France between Arras and Cambrai, came from Ontario-based McMaster University Library’s extensive World War I map collection – the largest digital collection of WWI maps in the world.

The map outlines France’s Western Front featuring cities and villages like Écoust-Saint-Mein, Arras, and Croisilles – all of which the film’s two protagonists, Lance-Cpl. Tom Blake (Dean-Charles Chapman) and Lance-Cpl. William Schofield (George MacKay), were required to pass through. The production team came across the map in early 2019 while going through McMaster University Library’s online map collection.

The Library’s Map Specialist Gord Beck was all too happy to help the 1917 team repurpose the map. “It’s a thrill to see McMaster’s maps used in this way. Once you make these maps available online, you’re constantly surprised by the applications they’re put to,” Beck said.

Related: How Esri helped Blade Runner 2049 take home an Oscar

Above, you can see the original version of the map showcasing Front Line and German divisions and regiments shown on the front immediately east of Arras, astride the River Scarpe from Gavrelle in the north, east of Monchy-le-Preux, to Croisilles in the south. The map covers front from Avion in the north to Bazentin-le-Petit in the south, and from west of Arras to east of Cambrai.

The Library’s map collection has been featured in other productions too, including a map from the WWII collection which was used in Brad Pitt-starrer Fury. In total, the Library has made more than 5,500 WWI and WWII maps and WWI aerial photos from its print collection available online.