A military reserve, active reserve, reserve formation, or simply reserve, is a group of military personnel or units that is initially not committed to a battle by its commander, so that it remains available to address unforeseen situations or exploit sudden opportunities. Such a force may be held back to defend against attack from other enemy forces, to be committed to the existing battle if the enemy exposes a vulnerability, or to serve as relief for troops already fighting. Some of the different categories of military reserves are: tactical reserve, operational reserve, and strategic reserve.
A military reserve is different from a military reserve force, which is a military organization composed of military personnel who maintain their military skills and readiness in a long-term part-time commitment to support their country if needed. Military reserve refers to specific trained pre-organized forces operating on an on-call basis from the main military force. Each member acts in combat as a regular soldier.
This section's factual accuracy is disputed .(February 2017)
The concept of reserve forces dates at least to[ citation needed ] early Roman legionary formations. In the early Roman legion, the soldiers were divided by wealth and age, with the poorer and younger Hastati forming the first line, followed by the Principes, and the wealthier and older Triarii. The first two lines were expected to do the majority of the fighting, with the third line held in reserve, both as a last resort and to deter routing.[ citation needed ]
In the modern battlefield, reserves exist at all levels, from a platoon held back from a company level engagement, to whole army corps consisting of armoured and mechanised divisions which are held in reserve with the purpose of exploiting a breakthrough or containing an enemy advance. Typically what is a reserve for one headquarters is not the reserve for a higher headquarters (though depending on the setup they may be). So if one of a battalion's companies is held in reserve during a battle, the company is considered to be a reserve for the battalion but not for the brigade or the division, since it is committed to action in its parent battalion sector. Similarly the British Reserve Army of World War I and the American Fifteenth Army of World War II were only reserves in their theater, as far as the national Headquarters was concerned, they were committed since they were not available to be sent for action in any other theater.
Deciding when, where, and how to employ reserves is one of the most important choices a commander makes. Usually only a part of the reserves are utilised at any given time, since these are often sufficient to accomplish the task at hand. Committing the entire reserve at once - the "all reserves forward" order - is only considered in moments of extreme crisis, when it is clear the enemy will not be stopped otherwise. In the event of reserves being sent forward to exploit a breakthrough, some are typically held back to deal with a potential counterattack. Reserves can also be employed to relieve troops in action, allowing those units to rest and regroup away from the front line.
Reserves may also exist in a broader sense: instead of being designated as the reserve in one tactical area, units and formations may be held back as forces available for responding to new strategic situations, or for fighting a decisive battle, as the battleship Yamato was.
Reserve troops—or lack thereof—have played a significant role in battles and campaigns throughout history, especially in the twentieth century. Nazi Germany deployed reserves from France and southern Europe to Tunisia, averting collapse in the wake of Operation Torch, and later to Italy, assuming control over most of that country after the Allied landing and the Italian surrender. Conversely, the lack of reserves to deal with the Allied landings in Sicily compelled the Germans to shift forces away from the Eastern Front, hampering the 1943 Kursk offensive, and the expenditure of their last reserves in the Battle of the Bulge contributed heavily[ citation needed ] to the general German collapse in 1945.
In the aftermath of World War I, the extensive colonial commitments of the United Kingdom left few battalions available for the Anglo-Irish War, which hindered the British ability to deal with the crisis.
At the Battle of Gaugamela, Alexander the Great held back his cavalry, using it first to deal with Persian flanking movements and later to exploit a gap in the enemy line and win the battle.
There have been many examples of reserves formations throughout history.
The Reserve Army was a field army of the British Expeditionary Force during the First World War. Under the command of Lieutenant General Sir Hubert Gough, the Reserve Army was formed on 23 May 1916, prior to the Battle of the Somme, and was renamed the Fifth Army in October of that year.
The intended purpose of the army was to carry out the breakthrough phase of the Somme offensive once General Sir Henry Rawlinson's Fourth Army had captured the German front-line trenches. For this role Gough was provided with the three British cavalry divisions and in June he was allocated an infantry corps of three divisions to support the advance.
Some armor heavy formations of India and Pakistan are designated as "strike corps" to take advantage of breakthroughs.
The II Corps was a corps-sized formation of the United States Army that was active in both World War I and World War II. It was originally formed and fought on the Western Front during World War I and was also the first American formation of any size to see combat in North Africa or Europe during World War II.
The German spring offensive, or Kaiserschlacht, also known as the Ludendorff offensive, was a series of German attacks along the Western Front during the First World War, beginning on 21 March 1918. The Germans had realised that their only remaining chance of victory was to defeat the Allies before the United States could fully deploy its resources. The German Army had gained a temporary advantage in numbers as nearly 50 divisions had been freed by the Russian withdrawal from the war with the Treaty of Brest-Litovsk.
The Battle of Loos took place from 25 September to 8 October 1915 in France on the Western Front, during the First World War. It was the biggest British attack of 1915, the first time that the British used poison gas and the first mass engagement of New Army units. The French and British tried to break through the German defences in Artois and Champagne and restore a war of movement. Despite improved methods, more ammunition and better equipment, the Franco-British attacks were largely contained by the Germans, except for local losses of ground. The British gas attack failed to neutralize the defenders and the artillery bombardment was too short to destroy the barbed wire or machine gun nests. German tactical defensive proficiency was still dramatically superior to the British offensive planning and doctrine, resulting in a British defeat.
General Sir Hubert de la Poer Gough was a senior officer in the British Army in the First World War. A favourite of the British Commander-in-Chief, Field Marshal Sir Douglas Haig, he experienced a meteoric rise through the ranks during the war and commanded the British Fifth Army from 1916 to 1918.
The Battle of Amiens, also known as the Third Battle of Picardy, was the opening phase of the Allied offensive which began on 8 August 1918, later known as the Hundred Days Offensive, that ultimately led to the end of the First World War. Allied forces advanced over 11 kilometres (7 mi) on the first day, one of the greatest advances of the war, with Gen Henry Rawlinson's British Fourth Army playing the decisive role. The battle is also notable for its effects on both sides' morale and the large number of surrendering German forces. This led Erich Ludendorff to later describe the first day of the battle as "the black day of the German Army". Amiens was one of the first major battles involving armoured warfare.
The Reserve Army was a field army of the British Army and part of the British Expeditionary Force during the First World War. On 1 April 1916, Lieutenant-General Sir Hubert Gough was moved from the command of I Corps and took over the Reserve Corps, which in June before the Battle of the Somme, was expanded and renamed Reserve Army. The army fought on the northern flank of the Fourth Army during the battle and became the Fifth Army on 30 October.
The first day on the Somme, 1 July 1916, was the beginning of the Battle of Albert (1–13 July), the name given by the British to the first two weeks of the 141 days of the Battle of the Somme in the First World War. Nine corps of the French Sixth Army and the British Fourth and Third armies attacked the German 2nd Army from Foucaucourt to the south of the Somme, northwards across the Somme and the Ancre to Serre and at Gommecourt, 2 mi (3 km) beyond, in the Third Army area. The objective of the attack was to capture the German first and second defensive positions from Serre south to the Albert–Bapaume road and the first position from the road south to Foucaucourt.
The Battle of the Ancre Heights, is the name given to the continuation of British attacks after the Battle of Thiepval Ridge from 26 to 28 September during the Battle of the Somme. The battle was conducted by the Reserve Army from Courcelette near the Albert–Bapaume road, west to Thiepval on Bazentin Ridge. British possession of the heights would deprive the German 1st Army of observation towards Albert to the south-west and give the British observation north over the Ancre valley to the German positions around Beaumont-Hamel, Serre and Beaucourt. The Reserve Army conducted large attacks on 1, 8, 21, 25 October and from 10 to 11 November.
The Battle of the Ancre(13–18 November 1916), was fought by the British Fifth Army, against the German 1st Army. The Reserve Army had been renamed the Fifth Army on 30 October. The battle was the last of the big British attacks of the Battle of the Somme. After the Battle of Flers–Courcelette the Anglo-French armies tried to press their advantage with smaller attacks in quick succession, rather than pausing to regroup and give the Germans time to recover. Subsequent writers gave discrete dates for the Anglo-French battles but there were considerable overlaps and continuities of operations until the weather and supply difficulties in mid-November ended the battle until the new-year.
The Attack at Fromelles 19–20 July 1916, was a military operation on the Western Front during the First World War. The attack was carried out by British and Australian troops and was subsidiary to the Battle of the Somme. General Headquarters (GHQ) of the British Expeditionary Force (BEF) had ordered the First Army (General Charles Munro and Second Army (General Herbert Plumer to prepare attacks to support the Fourth Army on the Somme, 50 mi to the south, to exploit any weakening of the German defences opposite. The attack took place 9.9 mi from Lille, between the Fauquissart–Trivelet road and Cordonnerie Farm, an area overlooked from Aubers Ridge to the south. The ground was low-lying and much of the defensive fortification by both sides consisted of building breastworks, rather than trenches.
The Battle of Albert is the British name for the first two weeks of British–French offensive operations of the Battle of the Somme. The Allied preparatory artillery bombardment commenced on 24 June and the British–French infantry attacked on 1 July, on the south bank from Foucaucourt to the Somme and from the Somme north to Gommecourt, 2 mi (3.2 km) beyond Serre. The French Sixth Army and the right wing of the British Fourth Army inflicted a considerable defeat on the German 2nd Army but from near the Albert–Bapaume road to Gommecourt, the British attack was a disaster, where most of the c. 57,000 British casualties of the day were incurred. Against the wishes of General Joseph Joffre, General Sir Douglas Haig abandoned the offensive north of the road to reinforce the success in the south, where the British–French forces pressed forward through several intermediate lines closer to the German second position.
The 1st Division is the main formation of the Australian Army and contains the majority of the Army's regular forces. Its headquarters is in Enoggera, a suburb of Brisbane. The division was first formed in 1914 for service during World War I as a part of the Australian Imperial Force (AIF). It was initially part of the Australian and New Zealand Army Corps (ANZAC) and served with that formation during the Gallipoli campaign, before later serving on the Western Front. After the war, the division became a part-time unit based in New South Wales, and during World War II it undertook defensive duties in Australia before being disbanded in 1945.
Deep operation, also known as Soviet Deep Battle, was a military theory developed by the Soviet Union for its armed forces during the 1920s and 1930s. It was a tenet that emphasized destroying, suppressing or disorganizing enemy forces not only at the line of contact, but throughout the depth of the battlefield.
The Raid on Tatsinskaya was a Soviet armoured raid deep into the German rear conducted by 24th Tank Corps under the command of Major General Vasily Mikhaylovich Badanov in late December 1942, during the last phases of the Battle of Stalingrad. It was designed to force the Germans to divert forces attempting to relieve the 6th Army encircled in Stalingrad. The Soviet force captured its objective, the Luftwaffe's airfield at Tatsinskaya, destroying over 72 aircraft on the ground, but was left cut off and without supplies. Despite the loss of most of the tank corps during the ensuing breakout, the raid was a great operational victory.
The United States campaigns in World War I began after American entry in the war in early April 1917. The American Expeditionary Force (AEF) served on the Western Front, under General John J. Pershing, and engaged in 13 official military campaigns between 1917 and 1918, for which campaign streamers were designated. The streamer uses the colors of the World War I Victory Medal ribbon which had a red center with a rainbow on each side of the center stripe and a purple edge. The double rainbow symbolizes the dawn of a new era and the calm which follows the storm.
The Battle of Mont Saint-Quentin was a battle on the Western Front during World War I. As part of the Allied Hundred Days Offensive on the Western Front in the late summer of 1918, the Australian Corps crossed the Somme River on the night of 31 August and broke the German lines at Mont Saint-Quentin and Péronne. The British Fourth Army's commander, General Henry Rawlinson, described the Australian advances of 31 August – 4 September as the greatest military achievement of the war. During the battle Australian troops stormed, seized and held the key height of Mont Saint-Quentin, a pivotal German defensive position on the line of the Somme.
The Capture of Regina Trench was a tactical incident in 1916 during the Battle of the Somme during the First World War. Regina Trench was the Canadian name for a German trench dug along the north-facing slope of a ridge running from north-west of the village of Le Sars, south-westwards to Stuff Redoubt, close to the German fortifications at Thiepval. It was the longest such German trench on the Western Front. Attacked several times by the Canadian Corps during the Battle of the Ancre Heights, the 5th Canadian Brigade of the 2nd Canadian Division briefly controlled a section of the trench on 1 October but was repulsed by counter-attacks of the German Marine Brigade, which had been brought from the Belgian coast. On 8 October, attacks by the 1st Canadian Division and the 3rd Canadian Division on Regina Trench also failed.
The Battle of Gembloux was fought between French and German forces in May 1940 during the Second World War. On 10 May 1940, The Nazi German Wehrmacht, invaded Luxembourg, The Netherlands and Belgium under the operational plan Fall Gelb. Allied armies responded with the Dyle Plan, intended to halt the Germans in Belgium, believing it to be the main German thrust. The Allies committed their best and most mobile to an advance into Belgium on 10 May and on 12 May, the Germans began the second part of Fall Gelb, the Manstein Plan an advance through the Ardennes, to reach the English Channel and cut off the Allied forces in Belgium.
Operation Michael was a major German military offensive during the First World War that began the German Spring Offensive on 21 March 1918. It was launched from the Hindenburg Line, in the vicinity of Saint-Quentin, France. Its goal was to break through the Allied (Entente) lines and advance in a north-westerly direction to seize the Channel Ports, which supplied the British Expeditionary Force (BEF) and to drive the BEF into the sea. Two days later General Erich Ludendorff, the chief of the German General Staff, adjusted his plan and pushed for an offensive due west, along the whole of the British front north of the River Somme. This was designed to first separate the French and British Armies before continuing with the original concept of pushing the BEF into the sea. The offensive ended at Villers-Bretonneux, to the east of the Allied communications centre at Amiens, where the Allies managed to halt the German advance; the German Army had suffered many casualties and was unable to maintain supplies to the advancing troops.
In 1917, during World War I, the armies on the Western Front continued to change their fighting methods, due to the consequences of increased firepower, more automatic weapons, decentralisation of authority and the integration of specialised branches, equipment and techniques into the traditional structures of infantry, artillery and cavalry. Tanks, railways, aircraft, lorries, chemicals, concrete and steel, photography, wireless and advances in medical science increased in importance in all of the armies, as did the influence of the material constraints of geography, climate, demography and economics. The armies encountered growing manpower shortages, caused by the need to replace the losses of 1916 and by the competing demands for labour by civilian industry and agriculture. Dwindling manpower was particularly marked in the French and German armies, which made considerable changes in their methods during the year, simultaneously to pursue military-strategic objectives and limit casualties.