thumb |An illustration of the Trojan Horse, from Histoire des jouets| right

The French , sometimes literally translated as ruse of war, is a non-uniform term; generally what is understood by "ruse of war" can be separated into two groups. The first classifies the phrase purely as an act of military deception against one's opponent; the second emphasizes acts against one's opponent by creative, clever, unorthodox means, sometimes involving force multipliers or superior knowledge. The term stratagem, from Ancient Greek (, 'act of generalship'), is also used in this sense.

are described from ancient to modern times, both in semi-mythical accounts and in well-documented events; they also feature in fiction. The term is given legal meaning within the rules of war. Good faith is required, but at least 17 different types of , including ambushes, false radio messages, the use of spies and the use of dummy guns, are considered legitimate as long as they do not involve treachery or perfidy. Landmines and similar traps can be considered perfidious under the rules in certain circumstances. Explicitly prohibited under article 23 of the Hague Convention of 1907 include improper use of a flag of truce or the military insignia of the enemy.

Examples

Ancient times

According to Homer's somewhat mythical account in the Iliad, the Greeks during the Trojan War pretended to give up their fruitless ten-year siege of the city of Troy and sailed away, leaving behind the Trojan Horse. After the Trojans pulled what they believed was a parting gift within the walls of the city, soldiers that had hidden inside the hollow horse during the previous night emerged and opened the city's gates, allowing the awaiting army to enter the city.

Prior to a naval battle with King Eumenes II of Pergamon, Hannibal sent a herald with a message for the opposing commander. That was a trick aiming to locate Eumenes's ship so that Hannibal could concentrate his forces against it.

Alexander the Great walked his men up and down a river continuously to condition his opponent, Porus, into a false sense of security in the belief that his whole army was searching for a ford. Then, under the cover of night Alexander marched a contingent of his men upriver and crossed the Indus, while his remaining forces marched south to their camp as they usually did. This feint allowed Alexander to hide his troops' location and win the Battle of Hydaspes in 326 BC.

As stated in the probably fictional account in Romance of the Three Kingdoms, Zhuge Liang tricked Sima Yi using the Empty Fort Strategy from Sun Tzu's The Art of War. Zhuge Liang sat upon the walls of the cities, his men far outnumbered by the Wei army which was advancing toward him. Zhuge Liang sat upon the walls and played his instrument, seemingly calm and composed, tricking Sima Yi into thinking that the Shu troops had hidden in the surrounding area for an ambush. Zhuge Liang was able to quickly flee the area as the Wei retreated.

Modern history

19th century

The Siege of Detroit was an early engagement in the War of 1812, where a smaller British-First Nations force, led by Major-General Isaac Brock and Shawnee leader Tecumseh, used bluff and deception to intimidate Brigadier General William Hull into surrendering the fort, the town of Detroit, and a dispirited American force that nevertheless outnumbered the British and First Nations. Intercepting American dispatches from Fort Detroit, Brock judged the morale of the American garrison to be low, and that the American general had a fear of First Nations in particular. Brock arranged for misleading letters to fall into American hands, stating an inflated figure of 5,000 First Nations warriors were already in Amherstburg, to simulate a larger First Nations force had attached themselves to his army. Prior to the siege, Brock also sent a letter demanding for surrender to Hull, stating: