After the Battle of the Trench, in which the Muslims tactically overcame their opponents while suffering very few casualties, efforts to defeat the Muslims failed, and Islam became influential in the region. As a consequence, the Muslim army besieged the neighbourhood of the Banu Qurayza tribe, leading to their unconditional surrender.
When Napoleon Bonaparte escaped from his enforced exile on the island of Elba, among other steps that the delegates of the European powers at the Congress of Vienna took was to issue a statement on 13 March 1815 declaring Napoleon Bonaparte to be an outlaw. The text includes the following paragraphs:
Consequently, as Napoleon was considered an outlaw when he surrendered to Captain Maitland of HMS Bellerophon at the end of the Hundred Days, he was not protected by military law or international law as a head of state, and so the British were under no legal obligation to either accept his surrender or to spare his life; however, they did so, exiling him to the remote South Atlantic island of Saint Helena.
The most famous early use of the phrase occurred during the 1862 Battle of Fort Donelson in the American Civil War. Brigadier General Ulysses S. Grant of the Union Army received a request for terms from the fort's commanding officer, Confederate Brigadier General Simon Bolivar Buckner. Grant's reply was that "no terms except an unconditional and immediate surrender can be accepted. I propose to move immediately upon your works." When news of Grant's victory—one of the Union's first in the Civil War—was received in Washington, D.C., newspapers remarked (and President Abraham Lincoln endorsed) that Ulysses S. Grant's first two initials, "U.S.", stood for "Unconditional Surrender," which would later become his nickname.
However, subsequent surrenders to Grant were not unconditional. When Robert E. Lee surrendered his Army of Northern Virginia at Appomattox Court House in 1865, Grant agreed to allow the men under Lee's command to go home under parole and to keep sidearms and private horses. Generous terms were also offered to John C. Pemberton at Vicksburg and (by Grant's subordinate, William Tecumseh Sherman) to Joseph E. Johnston in North Carolina.
Grant was not the first and only officer in the Civil War to use such a term. The first instance came when Confederate Brigadier General Lloyd Tilghman asked for terms of surrender during the Battle of Fort Henry. Flag Officer Andrew H. Foote replied, "no sir, your surrender will be unconditional". Even at Fort Donelson, when a Confederate messenger first approached Brig. Gen. Charles F. Smith, Grant's subordinate, for terms of surrender, Smith stated "I'll have no terms with Rebels with guns in their hands, my terms are unconditional and immediate surrender". The messenger was passed along to Grant but there is no evidence that either Foote or Smith influenced Grant's decision later on that day. In 1863 Ambrose Burnside forced an unconditional surrender of the Cumberland Gap and 2,300 Confederate soldiers and in 1864 Union General Gordon Granger forced an unconditional surrender of Fort Morgan.
The use of the term was revived during World War II at the Casablanca conference in January 1943 when American President Franklin D. Roosevelt (FDR) stated it to the press as the objective of the war against the Axis Powers of Germany, Italy, and Japan – and in doing so, surprised the leaders of his fellow Allied Powers. When Roosevelt announced this surrender condition at Casablanca, he did so referencing Ulysses S. Grant, stating that the famous general's initials, since the Civil War, had also come to stand for "Unconditional Surrender."
The term was also used at the end of the war, when Japan surrendered to the Allies. It has been estimated that it helped prolong the war in Europe through its usefulness to German domestic propaganda that used it to encourage further resistance against the Allied armies, and its suppressive effect on the German resistance movement since even after a coup against Adolf Hitler:
It has also been argued that without the demand for unconditional surrender Central Europe might not have fallen behind the Iron Curtain. "It was a policy that the Soviet Union accepted with alacrity, probably because a completely destroyed Germany would facilitate Russia's postwar expansion program."
One reason for the policy was that the Allies wished to avoid a repetition of the stab-in-the-back myth that arose in Germany after World War I, which attributed Germany's loss to betrayal by Jews, Bolsheviks and Socialists. The myth was used by the Nazis in their propaganda. It was felt that an unconditional surrender would ensure that the German people knew they had lost the war themselves and not because of a "stab in the back".
On 16 December 1971, Lt. Gen A. A. K. Niazi, CO of Pakistan Armed Forces located in East Pakistan signed the Instrument of Surrender handing over the command of his forces to Indian Army under General Jagjit Singh Aurora. This led to the surrender of 93,000 soldiers of the Pakistan's East Command and cessation of hostilities between the Pakistani Armed Forces and the Indian Armed Forces along with the guerrilla forces, the Mukti Bahini.
The signing of this unconditional surrender document gave Geneva convention guarantees for the safety of the surrendered soldiers and completed the independence of Bangladesh.
In siege warfare, the demand that the garrison unconditionally surrender to the besiegers is traditionally phrased as "surrender at discretion." For example, at the siege of Stirling during the 1745 Jacobite Rebellion:
It was also seen at the Battle of the Alamo, when Santa Anna asked Jim Bowie and William B. Travis for unconditional surrender. Even though Bowie wished to surrender unconditionally, Travis refused, retaliated by firing a cannon at Santa Anna's army, and wrote in his final dispatches:
The phrase surrender at discretion is still used in treaties, for example the Rome Statute that entered into force on July 1, 2002, specifies under "Article 8 war crimes, Paragraph 2.b" that:
This wording in the Rome Statute is taken almost word for word from Article 23 of the 1907 IV Hague Convention The Laws and Customs of War on Land: "...it is especially forbidden – ... To kill or wound an enemy who, having laid down his arms, or having no longer means of defence, has surrendered at discretion", and is part of the customary laws of war.