The following is an extract from Howard Anderson's excellent homepage The Die Hards - 1st Bn. Middlesex Regiment, 1914-1918. For most parts the text is quoted from the regimental history - Die-Hards in the Great War by Everard Wyrall - published in 1926-1930. 1)
The headlines, illustrations and the postscript on 19th Infantry Brigade have been provided by me. The map is from the regimental history.

(From The Die Hards - 1st Bn. Middlesex Regiment, 1914-1918)
British Infantry on Active Service, ca. 1914.
Contemporary postcard, published by
Gale & Polden, Aldershot.
At 5.30 a.m. the 1st Middlesex withdrew outposts and marched on Saintines, joining up with 19th Brigade Headquarters. About 6 o'clock the Brigade, having ascended the hills south of the village, was met by a messenger, who asked for assistance urgently for the 1st Cavalry Brigade and 'L' Battery, RHA, which were in difficulties at Néry and had suffered very heavily. Major F. G. M. Rowley 2), who temporarily commanded the 1st Middlesex, was ordered to march his Battalion off immediately towards Néry.
'The enemy appears to have got right round the Cavalry and had succeeded in placing some ten field guns within 800 yards of their camp. The Cavalry had a great many casualties, whilst their horses were lying dead in rows.' (War Diary, 19th Infantry Brigade)
Taking the nearest available Company ('D') with him, Major Rowley at once set off southwards towards Néry. On arriving at the village he reported to the G.O.C. 1st Cavalry Brigade, who said that the Middlesex could best render assistance by attacking the German guns which were firing from the high ground east of the village. On reaching the eastern exits of Néry, 'D' Company and the two Battalion machine guns under Lieutenant Jefferd came into action against the hostile battery. Rapid rifle fire and machine gun fire was then opened, and after two minutes the German guns ceased firing.
Charge!
Contemporary, but slightly later, postcard,
published by Gale & Polden, Aldershot.
Major Rowley then ordered 'D' Company to advance and capture the guns. With bayonets fixed and a cheer, the Middlesex men rushed across the small intervening valley and captured eight of the guns which had been firing on the 1st Cavalry Brigade and 'L' Battery, RHA.
With the exception of some 12 dead or badly wounded Germans the gun crews had fled. A few minutes later the German limbers were seen about 1.000 yards away and fire was at once opened on them, but they retired rapidly and were seen no more. The guns were found to be undamaged, two of them being loaded. No horses, however, being available the sights were removed and the elevating gear damaged
Machine Gun in Action, ca. 1914.
Contemporary postcard by Edgar A. Holloway,
published by Gale & Polden, Aldershot.
Meanwhile the two machine guns under Lieutenant Jefferd, after assisting in silencing the hostile artillery, had moved towards the sugar factory in rear of 'L' Battery. Here they were under fire from the German gun escort, Lieutenant Jefferd being wounded 3).
About twenty minutes after the guns were captured, the German gun escort was seen retiring across the open from near the sugar factory, and on fire being opened on them about 25 surrendered. A little later some of the captured guns were brought away by the Cavalry, who had made up teams for the purpose 4). In the meantime one-and-a-half companies of the Middlesex, co-operating with a Cavalry Regiment, had captured a German field ambulance with a few prisoners, in the next village eastwards.
This small action, insignificant as it may seem, is of considerable importance to Middlesex men, as the 1st Battalion of the Regiment was the first British unit to capture German guns in the war.
The 4th Cavalry Brigade and 'I' Battery, RHA, from St. Vaast, and a composite battalion of troops from the 10th Brigade (4th Division) from Verberie, had likewise responded to the call for help, which had been sent to them as well as to the 19th Infantry Brigade.
The guns of 'I' Battery unlimbered and came into action, but as they did so 'L' Battery ceased firing, for all of its guns had either been put out of action or the gun teams killed or wounded.
After the action the general retirement was again continued, the Middlesex forming rearguard with the remainder of the 19th Infantry Brigade. 'Of the eight guns captured by Battalion at least four were brought away, remainder having to be left as not enough horses for them.' The Battalion billeted that night in Fresnoy.
The 1st Battalion withdrew outposts at 5.30 a.m. and marched off in a south-south-westerly direction through Othis on Dammartin. The 19th Brigade formed the rearguard, and about midday a message reached the Middlesex that General Briggs, with his Cavalry Brigade (i.e. 1st Cavalry Brigade), had a cavalry force of the enemy en l'air, and asked for the assistance of the guns of the rearguard. But the artillery could not find suitable gun positions, and nothing could be done.
From Dammartin the Middlesex pushed on to Longperrier, where the whole Battalion (with the 2nd Argyll and Sutherland Highlanders on the right and 2nd Royal Welch Fusiliers on the left) took up an outpost line, west of the village; the 1st Middlesex had also covered a distance of about 20 miles.
The immortal story of the gallant action of 'L' Battery, R.H.A., should be read in the Official History of the War.
The 19th Infantry Brigade to which 1st Bn. Middlesex Regiment belonged had been formed on 19 August 1914 from battalions hereto assigned to Lines-of-Communication duties, e.g. working parties for camp preparation, various guard duties etc.
The brigade was independent at first, assigned to various divisions as the situation demanded. From 30 August to 12 October 1914 it was part of III. Corps (Major-General W.P. Pulteney), together with 4th Division; in October it was transferred to 6th Division.
(Commander: Major-General L.G. Drummond) 5)
Attached:
Captain James Lochhead Jack (1880-1962), 1st Cameronians (Scottish Rifles), was the Brigade Staff Captain. His diary (Source 3) provides information on the Brigade and its various duties in the first months of the war.
Argyll and Sutherland Highlanders, A company in marching order, ca. 1912.
Contemporary postcard by Harry Payne, published by Raphael Tuck & Sons.
For a more 1914'ish look, one must imagine the kilts covered by khaki aprons, and the white gaiters substituted by khaki ones.
The lieutenant on the left would have worn a jacked with open collar, together with a khaki shirt and tie.
James L. Jack describes 2nd Bn. Argyll and Sutherland Highlanders as a very smart battalion, and its commanding officer, Lieutenant-Colonel H.P. Moulton-Barrett, was very proud of it.
At Néry, the 2nd Argyll and Sutherland Highlanders were also sent forward in support of 1st Cavalry Brigade, but arrived after the fighting. On seeing the breakfast prepared by the 5th Dragoon Guards, who have had no time to eat it, the Highlanders quickly disposed of it, with a healthy appetite.
Highlanders, Crossing a Square in Boulogne, 1914.
This contemporary coloured postcard, published by
Underwood & Underwood, New York, may show
2nd Bn. Argyll and Sutherland Highlanders
which landed in Boulogne on 11 August 1914.
Due to their Lines-of-Communications tasks, the units of the later 19th Brigade went to France ahead of the British Expeditionary Force, and were the first combatant troops of to land in France.
The 1st Bn. Middlesex Regiment and the 1st Bn. Cameronians landed at Le Havre; 2nd Bn. Welch Fusiliers landed in Rouen.
Captain, 1st The Cameronians
(Scottish Rifles), 1914.
From Source 6.
The fact that the captain wears no spurs indicates that he is a platoon commander. Imagine black riding boots with spurs as footwear and a riding crop instead of the walking stick, Captain James L. Jack could have had a similar appearance when he went to Néry together with the advance guard of 1st Middlesex. His orders were "to ride there, find out the situation, and tell General Briggs that assistance is coming at once."
In the rifle regiments officers wore black leather equipment, where as officers in other infantry regiments wore brown leather, as shown on the postcard On Active Service shown previously. The glengarry cap is rifle green, described by Jack as being almost black. The walking stick used by officers in Scottish regiments had a more "rural" look than the plain sticks used by officers in other regiments.
Per Finsted
Notes:
1) Bibliographic data from Naval & Military Press.
2) Major F. G. M. Rowley was promoted Lieutenant-Colonel on 1st September, 1914.
3) Lieutenant Jefferd was severely wounded; for his gallantry he was awarded the French Croix de Chevalier de la Légion d'honneur. (From: The Middlesex Regiment 1755-1966, The Great War, Mons to Ypres, 1914)
4) According to Source 1, the Commander Royal Artillery, 4th Division, ordered 37th (Howitzer) Brigade, Royal Field Artillery 'to provide limbers to bring away any enemy guns that were worth moving'. Three German guns were moved away, later to be exhibited on Horse Guards Parade, London, however wrongly labelled 'Captured at Le Cateau'.
5) The Brigade Commander was wounded 26 August 1914 at Le Cateau. He was superseded by the senior battalion commander - Lieutenant-Colonel E.E. Ward, 1st Bn. Middlesex Regiment (killed in action, 21 October 1914).