Battle of Arras
In October, 1914, the French Tenth army attempted to outflank German forces on the Western Front by advancing along a line between Arras and Lens. After initial progress towards Douai was forced to withdraw after a counter-attack from Crown Prince Rupprecht and the German Sixth Army. The French Army lost Lens to Germany, but was able to retain Arras.
Primary Sources
(1) William Beach Thomas reported the offensive at Arras in the Daily Mail (10th April, 1917)
Near Arras our troops leapt to the attack in the midst of such artillery fire as the world has never seen. It was accompanied by an onslaught of strange engines of war, while overhead, as soon as the clouds allowed, our aeroplanes, moving at 130 miles an hour, rushed to tackle any German machines they could find.
From this vantage-point, where the full panorama from Vimy to Tilloy was etched in flames, I write immediately after watching the first storming. It is too early to give more than partial news, but the famous divisions directly in front of me, both of which I had before seen throw themselves on an entrenched and buttressed enemy, went straight through to their goal.