In 1914 The Gold Coast, now named Ghana, was a British possession on the West African Coast. The territory maintained a very efficient infantry battalion "The Gold Coast Regiment" that contained two 2.95-inch mountain guns as integral artillery support. On 17 June 1914 a regular army officer of The Border Regiment was seconded for service with the Colonial Office and posted to The Gold Coast Regiment. He was Lieutenant John Lawrence Leslie-Smith, and he had arrived in theatre just in time. In August 1914 the Gold Coast Regiment, along with French colonial troops, invaded and captured Togoland, now named Togo, an adjacent German colony. The Gold Coast Regiment was then involved in a much tougher operation to subjugate German Cameroons. The German troops in the south of that colony fought well against the French and British invasion, until in February 1916 they finally withdrew across their southern border into Spanish Guinea, where they were interned. On 8th August 1915 during severe fighting in thick bush north of the Spanish Guinea border, the Gold Coast Regiment had taken 29 casualties, one of the wounded being Lt Leslie-Smith. John recovered from his wound, was promoted to Captain, and then took part in the Gold Coast Regiment's campaign in German East Africa (now named Tanzania).
In German East Africa the Gold Coast Regiment quickly earned a reputation as first-class infantrymen. White troops from England and South Africa - and Sepoys from India - quickly succumbed to the tropical diseases and harsh climatic conditions prevalent in East Africa. At the end of the campaign the only British battalions remaining in the field were African infantry.
In July 1917 the Gold Coast Regiment was involved in operations between Kilwa and Lindi on the southern coast of German East Africa. On 19 July the Regiment advanced towards a known enemy position as part of a column manoeuvre to seize water holes at Narungombe, and quickly became embroiled in fierce fighting in high grass. Other units in the column deployed on either side of the Gold Coasters, as did two other columns in the vicinity, but when British shells caused a grass-fire on the left flank the South African and Indian troops there withdrew, leaving that flank open.
The right flank units held their ground and a general advance was ordered, some of the Gold Coast Regiment charging into and seizing enemy trenches, but without support on the left flank the captured position could not be held. A withdrawal was ordered through the bush and defensive positions dug. During the night the German troops withdrew, having achieved their objective of making the British pay a heavy price for the seizure of the Narungombe water-holes. The Gold Coast Regiment had lost 20% of its effective strength – 37 men killed and 114 wounded. Amongst those severely wounded was Captain J.L. Leslie-Smith.
In a supplement to the London Gazette dated 7 March 1918 an award of a Military Cross was made to Capt. John Lawrence Leslie-Smith, Bord. R
"For conspicuous gallantry and devotion to duty. He led his company across the open under heavy hostile fire of every description to a point within 150 yards of the enemy trenches, where he established himself, thereby enabling troops to be deployed on his flanks and to carry the enemy trenches from that position. Although wounded he commanded his men throughout the day with the greatest gallantry and determination."
John Leslie-Smith displayed his usual resilience, recovering from his wounds and resuming his appointment with the Gold Coasters. In May 1918 the Gold Coast regimental history mentions his excellent patrol work in Portuguese East Africa (now named Mozambique), where the Regiment was fighting.
Finally, in July and August 1918 John and his tough Gold Coasters sailed from Portuguese East Africa back home to West Africa. Their Regiment had fought proficiently and hard losing 215 men killed, 725 wounded, 13 missing, 270 died of disease and 567 invalided out of theatre. The regimental strength had averaged 900 men and continuous drafts from the Gold Coast had maintained that strength.
After the war John Leslie-Smith returned to regimental duties with the Border Regiment, relinquishing the temporary rank of major that he had been granted in 1918. The December 1926 Army List shows him as the senior Captain in the regiment.