The Battle of Loos marked a major turning point in the war – and saw Scottish battalions suffer some of their most devastating losses.
The campaign was the largest attack from the British military that year and marked the first time they used chlorine gas as a weapon – something that would be widespread for the remainder of the war.
The entirety of the Gordon Highlanders battalions in France took part in the 13-day offensive from September 25 to October 8.
This included an order given to the 1/4th Battalion to take part in a diversionary attack where they were guaranteed to suffer heavy losses.
Ruth Duncan, curator at the Gordon Highlanders Museum, said: “The big action was at Loos in September.
“Pretty well all the Gordons battalions were involved over the fighting.
“1/4th Battalions took part in a diversionary attack where they were essentially told going into it that they were the sacrificial element.
“They were told that they were going to be a diversion and that was just how it would be. It was pretty grim.
“That may have included the University Company – which was a company of OTC officers from Aberdeen University who all joined up together. They were known as U-Company.
“There was pretty close to none of them left by the end of the action.
“Loos was very hard-fought fighting.
“There were tens of thousands of casualties and there was a really heavy Scottish involvement.
“About one in three of the fallen were Scottish, such was the concentration of Highland soldiers at that time on that battlefield.”
The first use of chemical weapons on the Western Front occurred earlier in April 1915, at the Second Battle of Ypres by the German military.
The Battle of Loos marked the first time Britain used poisonous gas as a weapon, with horrifying consequences.
Ruth said: “There were nearly 6,000 gas canisters unleashed before the infantry attacked, but unfortunately, the wind changed direction and blew back on a lot of them.
“That was the first time it was used by the British Army and in successive battles throughout the next few years, it would continue to be used.”
The impact of chemical weapons could be seen on both the health of soldiers and their morale.
Ruth said: “Chemical warfare was certainly different and could kill or wound people so badly that they would be taken out from the war or would struggle to recover.
“A weapon on that scale would certainly have the potential to make an impact on both sides of the fighting.
“These weapons were in their infancy and being used for the first time, so there were elements where things didn’t go right.
“The different types had different effects on people and could add to misery at a very basic level – sitting in these hoods waiting for the gas to clear was the absolute minimum suffering you could go through.
“Chlorine gas would cause your lungs to fill up, mustard gas would cause terrible blistering – which for Highland soldiers was particularly bad because they wore kilts so their legs and knees would be exposed.
“It really had the potential to impact people’s morale as well as their physical wellbeing from a small-scale level through to really major and upsetting wounds or complications they would have to live with for the rest of their lives.”