The original temporary Cenotaph was erected in 1919 for a parade celebrating the end of the First World War, at which more than 15,000 servicemen, including French and American soldiers, saluted the monument.

The permanent Cenotaph was unveiled by King George V on 11 November 1920 in a ceremony combined with the repatriation of the Unknown Warrior, an unidentified British serviceman to be interred in Westminster Abbey.

[b][3][6][7] From 1915, the British government prohibited the repatriation of the bodies of men killed overseas, meaning that most bereaved families did not have a nearby grave to visit and thus war memorials became a focal point for their grief.

The government, fearful that revolutionary ideologies such as Bolshevism might start to take hold, hoped the parade and a central saluting point would unite the nation in celebrating the victorious conclusion to the war and commemorating the sacrifice of the dead.

[21][29][30] Four days after the parade, William Ormsby-Gore, Member of Parliament for Stafford—an army officer who fought in the war and was part of the British delegation at Versailles—questioned Mond about the Cenotaph in the House of Commons, and asked whether a permanent replacement was planned.

The following week, The Times published an editorial calling for a permanent replacement (though the writer suggested that there was a risk of vehicles crashing into the Cenotaph in its original location and that it be built on nearby Horse Guards Parade); many letters to London and national newspapers followed.

He replaced the real laurel wreaths with stone sculptures and added entasis—subtle curvature, reminiscent of the Parthenon, so that the vertical surfaces taper inwards and the horizontals form arcs of a circle.

[34][35] He wrote to Mond: I have made slight alterations to meet the conditions demanded by the setting out of its lines on subtle curvatures, the difference is almost imperceptible but sufficient to give it a sculpturesque quality and a life, that cannot pertain to rectangular blocks of stone.

[34][37] The only other significant alteration Lutyens proposed was the replacement of the silk flags on the temporary Cenotaph with painted stone, fearing that the fabric would quickly become worn and look untidy.

A diary entry by Lady Sackville from August 1920 records Lutyens complaining bitterly about the change, though documents in The National Archives suggest that he had been aware of it six months previously.

Greenberg describes this section as "quietly establish[ing] the memorial's overall character: an outward appearance of simple repose which, on close observation, shows itself to be dependent on the more complex forms of its masses".

According to Winter, the Cenotaph "managed to transform a victory parade [...] into a time when millions could contemplate the [...] inexorable reality of death in war," and was "a work of genius because of its simplicity.

[64] Jenny Edkins, a British political scientist, also draws a parallel between the Cenotaph and the Vietnam Memorial and the unexpected public acclaim that both received immediately after their unveiling.

Edkins observes that the Tomb was intended to "provide a grave for those who had none" and to become a focal point for the mourning of those buried overseas, but that the Cenotaph became much more popular as a site for both individual commemoration and public ceremonies.

[70] The German-American historian George Mosse noted that most countries involved in the First World War eventually adopted the concept of burying an unidentified soldier, but in London the Cenotaph fulfilled the same purpose, despite the tomb in the abbey.

The king was to unveil the Cenotaph, this time with Lutyens in attendance, along with other members of the royal family, the prime minister, and Randall Davidson, the Archbishop of Canterbury (the Church of England's most senior cleric).

[79] The king placed a wreath of roses on the Unknown Warrior's coffin, and the cortege continued its journey—His Majesty, the other royals, Lloyd George, and the archbishop following the gun carriage to the abbey.

Whitehall was closed to traffic for several days after the ceremony and wounded soldiers, other veterans, and members of the public began to file past the Cenotaph and lay flowers at its base.

[88] In the later 1920s, several proposals emerged for modifications to the Cenotaph, including the addition of life-size bronze statues at its corners, and installing a light inside the wreath at the top to emit a vertical beam, but all were rejected by the Office of Works on Lutyens's advice.

[89] A group of 5,000 unemployed men, on an anti-capitalist protest, paraded past the Cenotaph in 1921 and laid wreaths at its base; several with explicit political messages were removed.

The following day, Captain James Sears, a First World War veteran and prospective Labour Party parliamentary candidate, removed the entire wreath and threw it in the river.

In the Cenotaph's early years, the service was informal and crowds gathered round the memorial to pay their respects and lay tributes, but the ceremony gradually became more formal, and has changed little since the 1930s.

[129][130] A few days after the unveiling, Lloyd George wrote to Lutyens: "the Cenotaph, by its very simplicity, fittingly expresses the memory in which the people hold all those who so bravely fought and died" in the war.

Presenting the medal, the institute's president, John Simpson, described the Cenotaph as "the most remarkable of all [Lutyens's] creations [...] austere yet gracious, technically perfect, it is the very expression of repressed emotion, of massive simplicity of purpose, of the qualities which mark those whom it commemorates and those who raised it.

A 1936 novel by Irene Rathbone with an anti-war theme, They Call it Peace, concluded with a scene set at the Cenotaph in which two women complete pilgrimages to the monument, one to honour the dead and one feeling that the deaths were in vain.

Laurence Binyon's "For the Fallen" (1914) is closely associated with the Cenotaph, having been recited at its unveiling, and commonly features in remembrance services,[143][144][145] particularly the fourth stanza, which concludes: At the going down of the sun, and in the morning, we will remember them.

[147] According to one study of British war memorials, the Cenotaph's "deceptively simple design and deliberately non-sectarian message ensured that its form would be adopted widely, with local variations".

[157] Borg observed that there was no agreed standard for war memorials, with wide variations in design, though Lutyens's Cenotaph and Sir Reginald Blomfield's Cross of Sacrifice came closest.

[48] Such was the impact of the Cenotaph that even Blomfield, a great rival of Lutyens, drew on it for his Royal Air Force Memorial a short distance away on the bank of the River Thames.

[152] According to King, the Cenotaph's popularity with the public and its widespread use and adaptation by other artists, including professional rivals, showed the extent to which it became common property rather than a concept exclusive to Lutyens.