[11] Joining the 4th Battalion of his regiment at Nowshera[12] in India, Wilson served with it during the Second Anglo-Afghan War 1878–79, including the capture of Ali Masjid and the expedition in the Kunar Valley.

[23] After peace was declared in May 1902, he left South Africa on board the SS Bavarian and arrived in the United Kingdom the following month.

[30] After completing his five-year period of command, he was appointed assistant adjutant general of the South Army in India, in the grade of GSO1.

[33][34] Wilson's 12th Brigade formed part of the 4th Division of the British Expeditionary Force (BEF), ready to go overseas in the event of hostilities.

The division arrived at the front on 26 August, hungry, wet and weary after a night march, and was rushed into action at the Battle of Le Cateau.

[35] Wilson's 12th Brigade was taken by surprise and suffered heavy casualties, but rallied and held the extreme left of the British line until the BEF was able to retreat.

[37] The BEF next moved to the Ypres sector, the 4th Division detraining at St Omer and taking part in the Battle of Armentieres.

Influenced by his sluggish corps commander, Lieutenant General Pulteney, Wilson did not push on, and even withdrew a battalion that was making good progress, but he did eventually secure the crossings of the River Lys and the town of Armentieres.

[43] Wilson was made a Knight Commander of the Order of the Bath (KCB) in June that year,[44] and in September was promoted to temporary lieutenant-general[45] as GOC of the newly organised XII Corps.

The BSF's commander, Lieutenant General Sir George Milne, who had replaced Mahon in May 1916, decided that his manpower was too limited, and reduced Wilson's plan to a smaller assault on the first defence line only, preceded by a three-day bombardment to neutralise enemy batteries and destroy trenches and barbed wire.

The assault troops managed to cross no man's land, but it was difficult to get information back to HQs, and some companies simply disappeared.

On 21 September the downcast men of the BSF were stunned to be ordered to pursue the retreating Bulgarians, with XII Corps in the lead.

Wilson spent the next two years dealing with the complexities of the occupation, arranging the handover of Turkish munitions and defences, and the repatriation not only of released Allied POWs but of some 10,000 German troops left behind in Turkey.