He was frustrated by the reluctance of his superior, General Joseph Joffre, who was initially preoccupied by French attacks into Lorraine and the Ardennes, to appreciate the danger of the German march through Belgium.

[7] He was made a Général de Division in 1911 and Joffre, who thought him “a veritable lion”, included him on the shortlist of three for Deputy Chief of the General Staff that year.

Henry Wilson claimed – in an after dinner speech when he observed XX Corps manoeuvres in September 1913 – that Lanrezac had told him that he only knew the English phrases “Beautiful woman”, “kiss me quick” and “beefsteak and potatoes”, but that these were enough to travel the world.

[12] A letter which he wrote to the Governor of Maubeuge on 23 June suggests he thought the Germans would not come west of the River Sambre (i.e. that they would make a wider turning movement through Belgium than Joffre was assuming, but less so than they would actually attempt in the event).

[19] Lanrezac was already sufficiently concerned (11 August) about the German movement into Belgium to obtain permission to deploy one of his corps at Givet on the Meuse.

[20] Liège fell on 12 August, on which day senior British generals were still arguing, in London, as to how far forward the BEF should be deployed.

Lanrezac was ordered to deploy into the angle of the Rivers Sambre and the Meuse, requiring him to make a march of 120 kilometres in 5 days.

[27] [28][29][30] The British liaison officer Edward Spears later wrote that Lanrezac's reputation as an academic lecturer made him “the star turn” of the French Army.

The British commander Sir John French, at his meeting with Joffre on 16 August, was advised to hurry up and join in Lanrezac's offensive, as he would not wait for him to catch up.

[32][33] Spears described Lanrezac as “a big flabby man” with a habit of hitching his spectacles behind his ear, whilst Sir John, who disliked him, later described him as “a Staff College pedant” with no practical ability at command in war.

[35] Concerned at having to guard against a German Meuse crossing south of Sedan, at Mezieres, or (most likely) at Namur north of Givet, Lanrezac urged that he be allowed to retreat to Maubeuge to avoid being flanked.

Sir John, who had cancelled his own planned advance on news that Lanrezac had asked to fall back, agreed to hold his position.

[55][56] With his left and centre driven from the Sambre and the Germans threatening a Meuse crossing on right, [57] in Holger Herwig's view, Lanrezac's retreat from Charleroi may well have saved Fifth Army from annihilation.

[59] Lanrezac's retreat after the Battle of Charleroi (21–3 August) arguably saved the French army from decisive defeat as it prevented the much sought envelopment of the Schlieffen plan.

[60] Churchill later wrote:"The French Fifth Army had no sooner completed with severe exertions its deployment on the Sambre, and the British Army by forced marches had no sooner reached the neighbourhood of Mons, when the overwhelming force of the German turning movement through Belgium fell upon them ... [Sir John French] accepted [Joffre's wish to attack, even on the left] with implicit faith.

"[61] Sordet, whose cavalry were holding the gap between the two forces, had telegraphed to Lanrezac at 8pm on the 23rd that Sir John was pulling back to the line Bavai-Maubeuge (in fact this was a slight misunderstanding, as he was just making inquiries about the possibility doing so), and asked if he should “keep to [his] mission on its left”.

She also scoffed at Spears’ claim that “no evidence” had been found, observing that Adolphe Messimy testified at the postwar Briey hearings that there were 25 to 30 million relevant documents for the period in the archives.

[63] On the morning of 26 August, while the BEF II Corps was engaged at the Battle of Le Cateau, Sir John French had a hostile meeting with Joffre and Lanrezac at Saint-Quentin.

Lanrezac was only reluctantly persuaded by his chief of staff to attend, and before Joffre's arrival he was observed loudly criticising both GQG and the BEF, making a poor impression on the junior officer who witnessed it.

Lanrezac had his pince nez hanging from his ear “like a pair of cherries” and gave the impression of being bored whilst Joffre was speaking.

[64][65][66][67] At the meeting with Joffre and Sir John French on 26 August, Lanrezac had expressed a willingness to counterattack, but only after he had first retreated to a better position.

He later recorded that he had been struck by Lanrezac's tired appearance, and that he had a “yellow complexion, bloodshot eyes,” and that a “heated” discussion ensued.

Spears recorded that Joffre, painfully aware that he could not allow the BEF to be crushed on French soil, exploded with rage.

In the event he was impressed by Lanrezac's cool demeanour and handling of the battle, before departing for an afternoon meeting with Sir John French.

[82] Although Terraine sees Guise as a French tactical victory, Herwig is critical of Lanrezac for holding back Franchet d’Esperey’s I Corps for much of the day, and for failing to exploit the gap between German Second and Third Armies.

[83] On 31 August, German cavalry, hampered by lack of fresh horseshoes and nails, almost penetrated behind French Fifth Army, almost capturing the British politician J.E.B.

[85] Lanrezac's harsh criticism of his superiors in the Staff Corps overshadowed his impressive ability to avoid envelopment by the Germans, and he was replaced by Louis Franchet d'Espérey just before the opening of the First Battle of the Marne.

Joffre later recorded that ever since the Battle of Guise, Lanrezac's normal tendency to criticise and argue about his orders had been exacerbated by fatigue, to the detriment of Fifth Army staff's morale.

Coming after criticism of the British in the memoirs of Huguet and Foch, the book was a great success, Harold Nicolson writing that he had especially enjoyed the "satirical" portrait of the "conceit(ed) ... arrogant and obese" Lanrezac.