How 'combined arms tactics' changed the face of warfare in WWI
By late 1915, the Western Front had turned into an industrial graveyard where trench systems and artillery barrages, backed by massed machine guns, had reduced entire offensives to piles of corpses.
At Loos, for instance, which was fought between 25 September and 8 October 1915, the British lost over 50,000 men with little to show for it, while at Verdun, which lasted from 21 February to 18 December 1916, the French and Germans suffered over 700,000 casualties between them without a clear victor.
Under this pressure, military planners had begun to search for alternatives. So, over time, a more organised way of fighting began to appear, one that required infantry, tanks, aircraft, and artillery to work together with careful timing and clear objectives.
This new 'combined arms tactics' changed the nature of offensive operations, and played a major part in breaking the deadlock that had gripped the front for years.
The failure of traditional tactics
At the start of the war, many European commanders still largely relied on battlefield ideas developed in the age of rifles and cavalry.
French generals often ordered infantry charges across open ground, since they trusted that sheer aggression would break enemy lines, while British officers generally held to the belief that disciplined musketry would hold off mass attacks and allow steady advances.
However, by the winter of 1914, those assumptions had collapsed. Trenches stretched from the Belgian coast to the Swiss frontier, and barbed wire and machine guns were supported by heavily built dugouts and made frontal attacks suicidal.
In response, generals had come to rely on long artillery barrages in the hope of destroying enemy defences before ordering men over the top.
At the Somme in July 1916, British guns fired over 1.5 million shells in a week-long bombardment intended to clear the path.
However, much of the German barbed wire remained intact, and defenders who had sheltered in heavily built bunkers quickly manned their machine guns once the shelling lifted.
The result was a disaster. British forces under General Douglas Haig suffered 57,000 casualties on the first day alone, including 19,000 dead, which made it the bloodiest single day in British military history.
The Newfoundland Regiment alone, at Beaumont-Hamel, lost over 700 men in about thirty minutes.
Technological innovation on the battlefield
Eventually, the enormous scale of failure encourged the development of new ideas.
Artillery crews had begun using aerial reconnaissance to correct their fire, while sound-ranging and flash-spotting techniques allowed them to locate enemy batteries.
Also, engineers laid telephone cables along trenches and dug saps to position forward observers.
By 1915, aircraft had become increasingly essential for intelligence-gathering and artillery spotting, and by 1916, the British introduced tanks into battle for the first time during the Battle of Flers-Courcelette.
These were Mark I tanks that were used on 15 September 1916, and although they frequently broke down and moved slowly, they could cross trenches and crush barbed wire, and the crews inside enjoyed some protection from rifle and machine gun fire.
Only thirty-two of the forty-nine deployed tanks reached the starting point.
Eventually, officers realised that these weapons offered no solution when used alone.
Tanks would become stranded without infantry, and infantry would be mown down without artillery support, while artillery could not adjust quickly without aerial observation.
The real value came from coordination. It was the French that introduced the barrage roulant, or 'creeping barrage', which allowed artillery to move forward in timed lifts, just ahead of advancing troops.
This was the first step in the formation of a crucial new strategy.
What was 'combined arms tactics'?
Essentially, combined arms tactics involved the careful combination of different military branches into a single operation.
Infantry, artillery, aircraft, and tanks operated together so that each type could make up for the others’ weaknesses and improve their strengths.
Infantry could pin enemy troops and clear trenches, while artillery could suppress strongpoints and destroy barbed wire.
At the same time, aircraft could identify enemy movements and correct shellfire and tanks could create breaches and shield advancing troops from direct fire.
Soon, examples of coordinated attacks became noticeably more common. At Vimy Ridge in April 1917, for example, Canadian forces under General Julian Byng rehearsed their assault in detail, and engineers built full-scale trench models behind the lines to help them prepare.
Artillery coordination was overseen by General Arthur Currie, which was timed down to the minute and supply dumps were positioned close to the front, with battalion movements synchronised with creeping barrages.
As a result, they seized one of the most heavily defended positions on the Western Front within four days.
At Cambrai in November 1917, British forces deployed over 300 tanks supported by infantry and aircraft.
The attack began on 20 November and broke through the Hindenburg Line.
Although the Germans counterattacked successfully by 30 November and the assault lacked sufficient reserves and suffered from tank breakdowns, which prevented the British from sustaining their initial breakthrough, it demonstrated that when multiple arms were used together, the attackers could achieve more in a single day than months of uncoordinated assaults.
The German Spring Offensives of 1918
After Russia had withdrawn from the war in 1917, Germany had shifted dozens of divisions to the Western Front, as they prepared for a final offensive before American troops arrived in large numbers.
General Erich Ludendorff launched Operation Michael on 21 March 1918, which was supported by new artillery tactics and infiltration units.
This assault formed part of the larger Kaiserschlacht, which was known as "Kaiser’s Battle."
German gunners no longer shelled trenches blindly. Instead, they used short but intense bombardments that targeted enemy headquarters, artillery batteries, and supply lines.
Gas shells and high explosives were used, along with smoke canisters, to disrupt coordination.
Meanwhile, specially trained Sturmtruppen often slipped past enemy strongpoints and sowed confusion in the rear.
Aircraft provided air cover and reconnaissance, while engineers cleared the way for follow-on troops.
This meant that German forces advanced up to 60 kilometres in some sectors, so they gained more ground in weeks than the Allies had in the previous two years.
However, within weeks, the offensive stalled. Supply lines failed, exhausted units could not hold on to their gains, and reinforcements arrived too slowly.
The spring offensives to a large extent showed the potential of coordinated attacks, and they also showed the problems that came when armies pushed too far ahead.
The Allied Hundred Days Offensive
After they had survived the German assaults, the Allies responded with a campaign that used combined arms warfare in its most effective way.
On 8 August 1918, British, Canadian, Australian, and French forces launched a surprise attack near Amiens, at which over 500 tanks led the charge, that was supported by coordinated artillery and low-flying aircraft and by advancing infantry.
Artillery crews had used aerial reports, sound ranging, and flash spotting to locate German guns, many of which were destroyed before the attack began.
No preliminary bombardment gave the enemy time to prepare, and instead the fire was sudden and precise, carefully timed to support each stage of the advance.
Allied infantry followed close behind the creeping barrage, while tanks crushed wire and silenced machine gun posts.
Engineers repaired roads and cleared obstacles under fire, and this allowed reserves and supplies to keep pace, while aircraft strafed trenches and bombed supply lines, confusing the defenders.
The German Army collapsed in several places, and Ludendorff later described 8 August as “the black day of the German Army.”
The Allies pushed forward over the next three months in a series of carefully planned offensives, and in that time they won back territory and broke down the German position piece by piece.
Over 12,000 German prisoners were taken on the first day of the Amiens assault.
In particular, Australian Corps commander General John Monash received praise for his careful use of infantry, tanks, artillery, and aircraft together, although the wider Amiens assault was planned and directed by British Fourth Army commander General Rawlinson.