The 51st (Highland) Infantry Division created the 26th Infantry Brigade as a second line duplicate of the 152nd Infantry Brigade; the 27th Infantry Brigade as a second line duplicate of the 153rd Infantry Brigade; and the 28th Infantry Brigade as a second line duplicate of the 154th Infantry Brigade.
On 25 August, the 26th Brigade became active and was assigned its commanding officer.
Two days later, the 9th (Highland) Infantry Division was activated, made up of the 26th Brigade; the 27th and 28th Brigades were assigned as they became active over the following two days.
All of the division's troops came from Highland regiments.
The 26th Brigade consisted of the 5th and 7th Battalions, Seaforth Highlanders, and the 5th Battalion, Queen's Own Cameron Highlanders.
The 27th Brigade included the 5th Battalion, Black Watch, and the 7th and 9th Battalions, Gordon Highlanders.
The 28th Brigade was formed with the 7th Battalion, Black Watch, and the 10th and 11th Battalions, Argyll and Sutherland Highlanders.
The division's first general officer commanding (GOC) was Major-General George Lindsay, who had been called out of retirement.

At the end of the First World War, Rosyth had been the main base of the Royal Navy (RN).
Until 1938, all three services of the British military had agreed that it should remain so in the event of war.
In April 1938, the Admiralty recognised that the Firth of Forth was vulnerable against the deployment of enemy naval mines, which would present a danger to ships, and impede the fleet's ability to intercept German ships attempting to steam into the Atlantic, and made the decision to move the main base of the RN's primary fleet (the Home Fleet) to Scapa Flow.
Rosyth would remain an important base for the RN, and home to one of four naval shore commands that were established, responsible for control of coastal waters and inspecting intercepted shipping.
Likewise, vital RN fleet support installations existed at Invergordon.
At the outbreak of the war, the division was assigned to Scottish Command.
The division's brigades were not kept intact, and the infantry battalions were dispersed across Scotland to protect these RN assets.

Two battalions, the 5th Seaforth and the 7th Gordon Highlanders were dispatched to Orkney to protect the base at Scapa Flow.
They were charged with the defence of the islands and the fleet, as well as the protection of vulnerable points.
The latter included the gun batteries on the island of Flotta, booms around the anchorage, and communication infrastructure across Orkney.
Three battalions were based around Fife, to defend Rosyth.
They included the 5th Black Watch, based in Alloa, west of Rosyth.
A further three battalions were based near Invergordon to protect the naval facilities, including the 5th Queen's Own Cameron Highlanders, based at Tain north of the Invergordon, which was assigned the task of protecting the fleet's oil containers at Invergordon.
The remaining battalion, the 7th Black Watch, was dispersed to protect vulnerable points around Fife and Perthshire, including the Forth Bridge.
In addition to these duties, the division was also responsible for training; a responsibility that was impeded by the lack of instructors and the required equipment.
The division was also used as a source of reinforcements for other units.
For example, the 5th Queen's Own Cameron Highlanders released over 200 men to a sister battalion.
These losses were made up over several months, by new waves of recruits and conscripts.

In October 1939, Commander-in-Chief, Home Forces Walter Kirke was tasked with drawing up a defensive plan to defend the United Kingdom from a German invasion, which was codenamed Julius Caesar.
In November 1939, the division was assigned a role in this initial defensive plan, which it retained until 1940.
The plan envisioned troops in the affected area immediately locating and defeating German parachutists, or cordoning off and thereby immobilising any German forces until the division could be relieved.
On 6 March, Lindsay returned to retirement.
He was replaced by Major
The 51st (Highland) Infantry Division created the 26th Infantry Brigade as a second line duplicate of the 152nd Infantry Brigade; the 27th Infantry Brigade as a second line duplicate of the 153rd Infantry Brigade; and the 28th Infantry Brigade as a second line duplicate of the 154th Infantry Brigade. On 25 August, the 26th Brigade became active and was assigned its commanding officer. Two days later, the 9th (Highland) Infantry Division was activated, made up of the 26th Brigade; the 27th and 28th Brigades were assigned as they became active over the following two days. All of the division's troops came from Highland regiments. The 26th Brigade consisted of the 5th and 7th Battalions, Seaforth Highlanders, and the 5th Battalion, Queen's Own Cameron Highlanders. The 27th Brigade included the 5th Battalion, Black Watch, and the 7th and 9th Battalions, Gordon Highlanders. The 28th Brigade was formed with the 7th Battalion, Black Watch, and the 10th and 11th Battalions, Argyll and Sutherland Highlanders. The division's first general officer commanding (GOC) was Major-General George Lindsay, who had been called out of retirement.
At the end of the First World War, Rosyth had been the main base of the Royal Navy (RN). Until 1938, all three services of the British military had agreed that it should remain so in the event of war. In April 1938, the Admiralty recognised that the Firth of Forth was vulnerable against the deployment of enemy naval mines, which would present a danger to ships, and impede the fleet's ability to intercept German ships attempting to steam into the Atlantic, and made the decision to move the main base of the RN's primary fleet (the Home Fleet) to Scapa Flow. Rosyth would remain an important base for the RN, and home to one of four naval shore commands that were established, responsible for control of coastal waters and inspecting intercepted shipping. Likewise, vital RN fleet support installations existed at Invergordon. At the outbreak of the war, the division was assigned to Scottish Command. The division's brigades were not kept intact, and the infantry battalions were dispersed across Scotland to protect these RN assets.
Two battalions, the 5th Seaforth and the 7th Gordon Highlanders were dispatched to Orkney to protect the base at Scapa Flow. They were charged with the defence of the islands and the fleet, as well as the protection of vulnerable points. The latter included the gun batteries on the island of Flotta, booms around the anchorage, and communication infrastructure across Orkney. Three battalions were based around Fife, to defend Rosyth. They included the 5th Black Watch, based in Alloa, west of Rosyth. A further three battalions were based near Invergordon to protect the naval facilities, including the 5th Queen's Own Cameron Highlanders, based at Tain north of the Invergordon, which was assigned the task of protecting the fleet's oil containers at Invergordon. The remaining battalion, the 7th Black Watch, was dispersed to protect vulnerable points around Fife and Perthshire, including the Forth Bridge. In addition to these duties, the division was also responsible for training; a responsibility that was impeded by the lack of instructors and the required equipment. The division was also used as a source of reinforcements for other units. For example, the 5th Queen's Own Cameron Highlanders released over 200 men to a sister battalion. These losses were made up over several months, by new waves of recruits and conscripts.
In October 1939, Commander-in-Chief, Home Forces Walter Kirke was tasked with drawing up a defensive plan to defend the United Kingdom from a German invasion, which was codenamed Julius Caesar. In November 1939, the division was assigned a role in this initial defensive plan, which it retained until 1940. The plan envisioned troops in the affected area immediately locating and defeating German parachutists, or cordoning off and thereby immobilising any German forces until the division could be relieved. On 6 March, Lindsay returned to retirement. He was replaced by Major
9th (Highland) Infantry Division