Obusier de 400 Modèle 1915/1916

The Obusier de 400 Modèle 1915/1916 was a French howitzer, which was converted during the first world war to the largest railway gun of the French army and was used both in the first and still in the second world war.

Because of the successes and the great penetrating power of the German guns in firing at the fortresses of Liège, Namur, Antwerp and Maubeuge, the French High Command also demanded heavy guns. These should be able to damage or destroy the increasingly fortified German positions, the light field guns already in use would not be sufficient for this task.

Some heavy coastal guns or decommissioned naval guns had already been converted to railway guns and used, as their penetration power was considered too low to destroy the German concrete plants and bunkers. Therefore even bigger guns with an even bigger caliber were demanded.

The St. Chamond company then began converting 400 mm naval guns into railway guns in mid-1915. For this purpose two railway wagons were connected with a steel frame. Since the centre of gravity of the guns was very top-heavy, the rear wagon had only 4 axles, the front one 6 axles. In order to be able to drive the construction around tighter curves, rotating platforms were mounted on the front as well as on the rear wagon, so that the entire construction could be aligned more flexibly.

The guns used were naval guns which had already been taken out of service, from which warships they were taken is not known. They had a Welin breech and used separate cargoes and projectiles. For loading the pipe had to be lowered so that a loading platform could be raised at the rear part of the gun. A hydropneumatic recoil system was used to absorb the recoil. This allowed the gun to slide back a few metres after a shot, and then slide forward again to its original position.

In order to bring the railway gun into the firing position, the tracks had to be moved to the appropriate position. Then a deep hole had to be dug under the tracks so that the gun could retract when shooting at a high angle.



Drawing of the Obusier de 400 Modèle 1915/1916


Drawing of the Obusier de 400 Modèle 1915/1916



From the end of October 1915 the first of the altogether 8 Obusier de 400 Modèle 1915/1916 could be delivered in the variant 1915. 1916 followed after some modifications 4 further railway guns in the variant 1916, so that altogether 12 of the guns were built. With its 400 mm caliber the Obusier de 400 Modèle 1915/1916 belonged to the largest railway gun of the whole war used by the French army.



The first Obusier de 400 Modèle 1915/1916 were brought to the front at the end of October 1915


A Obusier de 400 Modèle 1915/1916 in her position at the western front



The first use of the war was made by the guns from 30 June 1916 during the Battle of the Somme. There they served as support for the upcoming offensive and fired at the German fortifications of the villages Herbécourt, Estrées and Belloy-en-Santerre, which were then only ruins.



A Obusier de 400 Modèle 1915/1916 gun during the Battle of the Somme


A Obusier de 400 Modèle 1915/1916 gun during the Battle of the Somme




The second use of the railway gun was during the reconquest of the fortresses near Verdun. For this purpose, the two guns of the 3rd Foot Artillery Regiment were set up 13 kilometres southwest of Baleycourt in order to be able to support the starting offensive on 21 October 1916. In the next 2 days about 373 of the deployed 370 and 400 mm guns alone were delivered. Especially the occupied forts Douaumont and Vaux were bombed. At the Fort Vaux alone on 23 October 1916 about 50 shells struck and destroyed the infirmary, several corridors, casemates and finally an ammunition depot, after whose fire the German soldiers had to give up the fort.



A Obusier de 400 Modèle 1915/1916 is loaded


A Obusier de 400 Modèle 1915/1916 is brought to the front



The last major deployment of the railway guns took place in April 1917 during the support of the offensive at Reims. There the German troops had strongly developed fortifications at Brimont, Witry-lès-Reims and Berru as well as bunkers and tunnels under Mount Cornillet and Mont-sans-nom. Through aerial reconnaissance and interrogations of captured German soldiers, the French High Command had an overview of the entrances and ventilation shafts of the German bunkers. In the middle of May 1917 the bombardment of the bunkers was started. First the entrances were bombed to block the escape of the soldiers. Then the ventilation shafts were bombed, so that the enclosed soldiers suffocated. A grenade was able to penetrate the 30 metre thick limestone layer above one of the bunkers and exploded inside the German bunker. Around 400 soldiers lost their lives.



One Obusier de 400 Modèle 1915/1916 in April 1917


Comparison of a grenade of a Obusier de 400 Modèle 1915/1916 and a French soldier



In addition to the French army, the 52nd artillery regiment of the Coast Artillery Corps of the American troops received 2 of the railway guns. On the basis of these guns, the USA built the railway howitzer M1918. Even after the First World War, the French railway guns served as the basis for other American railway guns and coastal artillery.



American soldiers invite a Obusier de 400 Modèle 1915/1916


American soldiers fire a Obusier de 400 Modèle 1915/1916



After the First World War, the remaining 10 French railway guns remained in depots as a reserve. When the Second World War broke out, 8 of the guns were used to reinforce the Maginot Line in Alsace and Lorraine. After the capitulation of France in 1940, the German Wehrmacht captured the guns and put them into service under the designation 40 cm howitzer (E) 752 (f). These were brought to the Eastern front at the beginning of the war against the Soviet Union and 6 of the guns were used for the siege of Leningrad, the other 2 guns were used for spare parts.




Data sheet:

Designation: Obusier de 400 Modèle 1915/1916
Manufacturing country: France
Introductory year: 1915
Number of pieces: 12 pieces
Calibers: 400 mm
Tube length: 10,65 meters
Range: Max. 16.000 meters
Weight: 137 tons






You can find the right literature here:


Flesh and Steel During the Great War: The Transformation of the French Army and the Invention of Modern Warfare

Flesh and Steel During the Great War: The Transformation of the French Army and the Invention of Modern Warfare Hardcover – October 30, 2018

Michel Goya’s Flesh and Steel during the Great War is one of the most thoughtful, stimulating and original studies of the conflict to have appeared in recent years. It is a major contribution towards a deeper understanding of the impact of the struggle on the Western Front on the theory and practice of warfare in the French army. In a series of incisive, closely argued chapters he explores the way in which the senior commanders and ordinary soldiers responded to the extraordinary challenges posed by the mass industrial warfare of the early twentieth century.

In 1914 the French army went to war with a flawed doctrine, brightly-colored uniforms and a dire shortage of modern, heavy artillery How then, over four years of relentless, attritional warfare, did it become the great, industrialized army that emerged victorious in 1918?

To show how this change occurred, the author examines the pre-war ethos and organization of the army and describes in telling detail how, through a process of analysis and innovation, the French army underwent the deepest and fastest transformation in its history.

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Breaking Point of the French Army: The Nivelle Offensive of 1917

Breaking Point of the French Army: The Nivelle Offensive of 1917 Hardcover – November 2, 2015

In December 1916 General Robert Nivelle was appointed Commander-in-Chief of the French armies fighting the Germans on the Western Front. He had enjoyed a meteoric rise to high command and public acclaim since the beginning of the war - he was a national hero. In return, he proclaimed he ‘had the formula’ that would ensure victory and end the conflict in 1917. But his offensive was a bloody and humiliating failure for France, one that could have opened the way for French defeat.

This is the subject of David Murphy’s penetrating, in-depth study of one of the key events in the history of the Great War. He describes how Nivelle, a highly intelligent and articulate officer, used his charm to win the support of French and British politicians, but also how he was vain and boastful and displayed no sense of operational security. By the opening of the campaign, his plan was an open secret and he had lost the ability to critically assess the operation as it developed. The result was disaster.

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They Shall Not Pass: The French Army on the Western Front 1914-1918

They Shall Not Pass: The French Army on the Western Front 1914-1918 Hardcover – May 19, 2012

This graphic collection of first-hand accounts sheds new light on the experiences of the French army during the Great War. It reveals in authentic detail the perceptions and emotions of soldiers and civilians who were caught up in the most destructive conflict the world had ever seen.
Their testimony gives a striking insight into the mentality of the troops and their experience of combat, their emotional ties to their relatives at home, their opinions about their commanders and their fellow soldiers, the appalling conditions and dangers they endured, and their attitude to their German enemy. In their own words, in diaries, letters, reports and memoirs - most of which have never been published in English before - they offer a fascinating inside view of the massive life-and-death struggle that took place on the Western Front.
Ian Sumner provides a concise narrative of the war in order to give a clear context to the eyewitness material. In effect the reader is carried through the experience of each phase of the war on the Western Front and sees events as soldiers and civilians saw them at the time. This emphasis on eyewitness accounts provides an approach to the subject that is completely new for an English-language publication.
The author’s pioneering work will appeal to readers who may know something about the British and German armies on the Western Front, but little about the French army which bore the brunt of the fighting on the allied side. His book represents a milestone in publishing on the Great War.

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Artillery in the Great War

Artillery in the Great War Hardcover – May 18, 2011

Artillery was the decisive weapon of the Great War - it dominated the battlefields. Yet the history of artillery during the conflict has been neglected, and its impact on the fighting is inadequately understood. Paul Strong and Sanders Marble, in this important and highly readable study, seek to balance the account.Their work shows that artillery was central to the tactics of the belligerent nations throughout the long course of the conflict, in attack and in defense. They describe, in vivid detail, how in theory and practice the use of artillery developed in different ways among the opposing armies, and they reveal how artillery men on all sides coped with the extraordinary challenges that confronted them on the battlefield. They also give graphic accounts of the role played by artillery in specific operations, including the battles of Le Cateau, the Somme and Valenciennes.Their work will be fascinating reading for anyone who is keen to understand the impact of artillery

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