Question: When did the battle occur for which William Johnstone Milne received the Victoria Cross?

full_context: Document 1: Richhpal Ram: Richhpal Ram VC (20 August 1899 – 12 February 1941) was an Indian recipient of the Victoria Cross, the highest and most prestigious award for gallantry in the face of the enemy that can be awarded to British and Commonwealth forces.
Document 2: William Allison White: William Allison White VC TD (19 October 1894 – 13 September 1974) was an English recipient of the Victoria Cross, the highest and most prestigious award for gallantry in the face of the enemy that can be awarded to British and Commonwealth forces.
Document 3: Victoria Cross: The Victoria Cross (VC) is the highest award of the United Kingdom honours system. It is awarded for gallantry "in the face of the enemy" to members of the British armed forces. It may be awarded posthumously. It was previously awarded to Commonwealth countries, most of which have established their own honours systems and no longer recommend British honours. It may be awarded to a person of any military rank in any service and to civilians under military command although no civilian has received the award since 1879. Since the first awards were presented by Queen Victoria in 1857, two thirds of all awards have been personally presented by the British monarch. These investitures are usually held at Buckingham Palace.
Document 4: Battle of Vimy Ridge: The Battle of Vimy Ridge was a military engagement fought primarily as part of the Battle of Arras, in the Nord-Pas-de-Calais region of France, during the First World War. The main combatants were the Canadian Corps, of four divisions, against three divisions of the German Sixth Army. The battle, which took place from 9 to 12 April 1917, was part of the opening phase of the British-led Battle of Arras, a diversionary attack for the French Nivelle Offensive.
Document 5: Battle of Verdun: The Battle of Verdun ("Bataille de Verdun", ] , "Schlacht um Verdun", ] ), fought from 21 February to 18 December 1916, was the largest and longest battle of the First World War on the Western Front between the German and French armies. The battle took place on the hills north of Verdun-sur-Meuse in north-east France. The German 5th Army attacked the defences of the Fortified Region of Verdun ("RFV, Région Fortifiée de Verdun") and those of the French Second Army on the right bank of the Meuse. Inspired by the experience of the Second Battle of Champagne in 1915, the Germans planned rapidly to capture the Meuse Heights, an excellent defensive position with good observation for the artillery to bombard Verdun. The Germans hoped that the French would commit their strategic reserve to recapture the position and suffer catastrophic losses in a battle of annihilation, not costly for the Germans because of their tactical advantage.
Document 6: Battle of Messines (1917): The Battle of Messines (7–14 June 1917) was conducted by the British Second Army (General Sir Herbert Plumer), on the Western Front near the village of Messines in West Flanders, Belgium, during the First World War. The Nivelle Offensive in April and May had failed to achieve its more ambitious aims, had led to the demoralisation of French troops and dislocated the Anglo-French strategy for 1917. The offensive at Messines forced the Germans to move reserves to Flanders from the Arras and Aisne fronts, which relieved pressure on the French. The tactical objective of the attack at Messines was to capture the German defences on the ridge, which ran from Ploegsteert (Plugstreet) Wood in the south, through Messines and Wytschaete to Mt. Sorrel, to deprive the German 4th Army of the high ground south of Ypres. The ridge commanded the British defences and back areas further north, from which the British intended to conduct the Northern Operation, an advance to Passchendaele Ridge and then capture the Belgian coast up to the Dutch frontier.
Document 7: Battle of Arras (1917): The Battle of Arras (also known as the Second Battle of Arras) was a British offensive on the Western Front during World War I. From 9 April to 16 May 1917, British troops attacked German defences near the French city of Arras on the Western Front. The British achieved the longest advance since trench warfare had begun, surpassing the record set by the French Sixth Army on 1 July 1916. The British advance slowed in the next few days and the German defence recovered. The battle became a costly stalemate for both sides and by the end of the battle the British Third and First armies had suffered about 160,000 casualties and the German 6th Army 125,000 casualties.
Document 8: Chhelu Ram: Chhelu Ram VC (10 May 1905 – 20 April 1943) was an Indian recipient of the Victoria Cross, the highest and most prestigious award for gallantry in the face of the enemy that can be awarded to British and Commonwealth forces.
Document 9: Vimy Ridge Day: Vimy Ridge Day is a day to commemorate the deaths and casualties of members of the Canadian Corps during the First World War Battle of Vimy Ridge. The holiday has been observed annually since 2003. It is not considered a public holiday.
Document 10: Victoria Cross (Canada): The Victoria Cross (VC) is the highest award of the United Kingdom honours system. It was previously awarded to Canada and other Commonwealth countries, most of which including Canada have established their own honours systems and no longer recommend British honours. Today, the Victoria Cross (French: "Croix de Victoria" ), created in 1993 and named in honour of the British Victoria Cross is the highest award within the Canadian honours system, taking precedence over all other orders, decorations, and medals. It is awarded by either the Canadian monarch or his or her viceregal representative, the Governor General of Canada, to any member of the Canadian Forces or allies serving under or with Canadian military command for extraordinary valour and devotion to duty while facing hostile forces. Whereas in many other Commonwealth countries the relevant version of the Victoria Cross can only be awarded for actions against the enemy in a wartime setting, the Canadian government has a broader definition of the term "enemy", and so the Victoria Cross can be awarded for action against armed mutineers, pirates, or other such hostile forces without war being officially declared. Recipients are entitled to use the post-nominal letters "VC" (for both English and French) and also to receive an annuity of C$3,000. The decoration has not been awarded since its inception.
Document 11: Battle of the Canal du Nord: The Battle of Canal du Nord was part of a general Allied offensive against German positions on the Western Front during the Hundred Days Offensive of World War I. The battle took place in the Nord-Pas-de-Calais region of France, along an incomplete portion of the Canal du Nord and on the outskirts of Cambrai between 27 September and 1 October 1918. To avoid the risk of having extensive German reserves massed against a single Allied attack, the assault along the Canal du Nord was undertaken as part of a number of closely sequenced Allied attacks at separate points along the Western Front. It began one day after the Meuse-Argonne Offensive, one day before an offensive in the Flanders region of Belgium and two days before the Battle of St. Quentin Canal.
Document 12: Nivelle Offensive: The Nivelle Offensive of 1917, was a Franco-British offensive on the Western Front in the First World War. The French part of the offensive was intended to be strategically decisive, by breaking through the German defences on the Aisne front within 48 hours, with casualties expected to be around 10,000 men. A preliminary attack was to be made by the French Third Army at St. Quentin and the British First, Third and Fifth armies at Arras, to capture high ground and divert German reserves from the French fronts on the Aisne and in Champagne. The main offensive was to be delivered by the French on the Chemin des Dames ridge (the Second Battle of the Aisne, "La bataille du Chemin des Dames" , "Seconde bataille de l'Aisne" and "Doppelschlacht Aisne-Champagne" ), with a subsidiary attack by the Fourth Army (the Third Battle of Champagne, the Battle of the Hills or Battle of the Hills of Champagne). The final stage of the offensive was to follow the meeting of the British and French armies, having broken through the German lines, with a pursuit of the defeated German armies towards the German frontier.
Document 13: Battle of the Hills: The Battle of the Hills (French: "Bataille des Monts" ) also known as the Battle of the Hills of Champagne and the Third Battle of Champagne, was a battle of the First World War that was fought from April–May 1917. The French Fourth Army offensive against the German 4th Army was intended to be auxiliary to that of the "Groupe d'armées du Nord" (GAN, Northern Army Group) along the Chemin des Dames, in the Second Battle of the Aisne. General Anthoine, commander of the Fourth Army planned a supporting attack but this was rejected by Nivelle and Anthoine planned a frontal attack by two corps on an 11 km front, to break through the German defences on the first day and commence exploitation the following day. The battle took place east of Reims, between Prunay and Aubérive, in the province of Champagne, along the Moronvilliers Hills.
Document 14: William Johnstone (VC): William Johnstone VC (6 August 1823 – 20 August 1857) was a Royal Navy sailor and a recipient of the Victoria Cross, the highest award for gallantry in the face of the enemy that can be awarded to British and Commonwealth forces. He enlisted and served as John Johnstone.
Document 15: William Johnstone Milne: William Johnstone Milne VC (21 December 1892 – 9 April 1917) was a Canadian soldier. Milne was a recipient of the Victoria Cross, the highest and most prestigious award for gallantry in the face of the enemy that can be awarded to British and Commonwealth forces. Milne was a Canadian soldier in World War I who received the VC at the Battle of Vimy Ridge on 9 April 1917.
ground_truth: 9 to 12 April 1917