The Battle of Arras was a major WWI battle. We toured the extensive caves created for the efforts of the British to surprise the Germans dug in the trenches. It’s a guided tour, of course. You could easily get lost even with the wall markings still largely in place. The English/French guide was very good, and there is an audio guide that kicks in with additional information while you walk to the next section.
Before 1916 the French manned the Arras line, then the British moved in. They brought in coal miner volunteers from New Zealand, called sappers, to dig towards the German lines. Their efforts produces extensive tunnels, . The idea was to allow some 24,000 troops to exit the tunnels close to the German trenches, to gain the upper hand by surprise, in coordination with a French attack. Tunnel tactics date well back in time, to thousands of years before the common era.
The battle took place 9 April to 16 May 1917. It was part of the Nieville Offensive, conceived by the French general of that name. The British assaulted from Vimy to the north-west to Bullecourt to the south-east. The Canadians captured Vimy Ridge. The Third Army advanced along the Scarpe River, which we took to get here. Per the guide the French did not move for several days, contrary to plans, and the British troops paused the attack after its initial success, allowing the Germans to recover. Nonetheless the British advanced further than any previous effort in the trench warfare phase of the War. The blood bath continued until late in 1918 when the US entry in the war helped turn the tide. We visited one of the cemeteries on the edge of town, meticulously maintained to this day.
Arras was nearly flattened by German bombing. Most of the populace fled, leaving just 1200 behind when the battle began.