A standing army, unlike a reserve army, is a permanent, often professional, army. It is composed of full-time soldiers (who may be either career soldiers or conscripts) and is not disbanded during times of peace. It differs from army reserves, who are enrolled for the long term, but activated only during wars or natural disasters, and temporary armies, which are raised from the civilian population only during a war or threat of war and disbanded once the war or threat is over. The term dates from approximately 1600, although the phenomenon it describes is much older.
The first known standing armies in Europe were in ancient Greece. The male citizen body of ancient Sparta functioned as a standing army, unlike all other city-states (Poleis), whose armies were citizen militias. The existence of an enslaved population of helots liberated the Spartiates from the need to work for a living, enabling them to focus their time and energy on martial training. Philip II of Macedon instituted the first professional army, with soldiers and cavalrymen paid for their service year-round, rather than a militia of men who mostly farmed the land for subsistence and occasionally mustered for campaigns.
Under the reign of Augustus, the first Roman emperor, a standing professional army of the Roman Empire was gradually instituted, with regularized pay. The maintenance of this professional force of legions was highly expensive, but supported the authority of the empire, not only as combat troops but also as provincial police forces, engineers, and guards. Legions were citizen volunteers entitled to a discharge bounty upon 25 years' of honorable service; supplementing the legions were the auxilia, auxiliary forces composed of non-citizens in the provinces who typically earned citizenship as a reward for service.
Prior to the influence of Oliver Cromwell, England did not have a standing army with professional officers or careerist corporals or sergeants. It relied on militia organized by local officials, private forces mobilized by the nobility and hired mercenaries from Europe. This changed during the English Civil War, when Cromwell formed his New Model Army of 50,000 men. This professional body of soldiers proved more effective than untrained militia, and enabled him to exert control over the country. The army was disbanded by Parliament following the Restoration of the Monarchy in 1660, and the Cromwellian model was initially considered a failure due to various logistical and political problems with the force.
The Militia Act of 1661 and 1662 prohibited local authorities from assembling militia without the approval of the King, to prevent such a force being used to oppress local opponents. This weakened the incentive for local officials to draw up their own fighting forces, and King Charles II subsequently assembled four regiments of infantry and cavalry, calling them his guards, at a cost of £122,000 from his regular budget. This became the foundation of the permanent British Army. By 1685 it had grown to 7500 soldiers in marching regiments, and 1400 men permanently stationed in garrisons. The Monmouth Rebellion in 1685 provided James II with a pretext to increase the size of the force to 20,000 men, and there were 37,000 in 1678, when England played a role in the closing stage of the Franco-Dutch War. In 1689, William III expanded the army to 74,000, and then to 94,000 in 1694.
Nervous at the power such a large force afforded the King whilst under his personal command, Parliament reduced the cadre to 7000 in 1697. Scotland and Ireland had theoretically separate military establishments, but they were de facto merged with the English force. The Bill of Rights 1689 officially reserved authority over a standing army to Parliament, not the King.
In his influential work The Wealth of Nations (1776), economist Adam Smith comments that standing armies are a sign of modernizing society as modern warfare requires the increased skill and discipline of regularly trained standing armies.
In the British Thirteen Colonies in America, there was a strong distrust of a standing army not under civilian control. The U.S. Constitution in (Article 1, Section 8) limits federal appropriations to two years, and reserves financial control to Congress, instead of to the President. The President, however, retains command of the armed forces when they are raised, as commander-in-chief. In the course of this constitutional debate, Elbridge Gerry arguing against a large standing army, compared it, mischievously, to a standing penis: "An excellent assurance of domestic tranquility, but a dangerous temptation to foreign adventure." After the Battle of Bladensburg in 1814, during the War of 1812, in which the Maryland and Virginia militias were soundly defeated by the British Army, President James Madison commented, "I could never have believed so great a difference existed between regular troops and a militia force, if I not witnessed the scenes of this day."