Written by David Whitaker and directed by Douglas Camfield, the serial was broadcast on BBC1 in four weekly parts from 27 March to 17 April 1965.

In this serial, the First Doctor (William Hartnell) and his travelling companions Ian Chesterton (William Russell), Barbara Wright (Jacqueline Hill), and Vicki (Maureen O'Brien) arrive in 12th century Palestine during the Third Crusade, and find themselves entangled in the conflict between King Richard the Lionheart (Julian Glover) and Saladin (Bernard Kay).

They also meet King Richard's sister Lady Joanna (Jean Marsh) and Saladin's brother Saphadin (Roger Avon).

He was fascinated by the Third Crusade, and found the historical figures effective material for a character drama, particularly the relationship between King Richard and his sister.

Story editor Dennis Spooner was impressed by the maturity and near-Shakespearean nature of Whitaker's scripts, and Camfield considered them the best he directed for the show.

The story received several print adaptations and home media releases, with the missing episodes reconstructed using off-air recordings.

In the confusion, Barbara is seized by a Saracen from behind while the rest of the TARDIS crew stop the attackers from killing William de Tornebu (Bruce Wightman), an associate of Richard the Lionheart (Julian Glover).

Barbara and William des Preaux (John Flint) are presented to Saladin's brother Saphadin (Roger Avon) by El Akir (Walter Randall), who mistakenly believes them to be King Richard and his sister Lady Joanna.

When des Preaux reveals their true identities, El Akir is furious; before he can act, Saladin (Bernard Kay) emerges and is intrigued by Barbara.

Ian is knighted so that he may serve as an emissary; he is sent to Saladin's court to both request the release of des Preaux and Barbara, and to offer the hand of the real Lady Joanna (Jean Marsh) in marriage to Saphadin in order to create peace.

One of the bandits, Ibrahim (Tutte Lemkow), ties him down with stakes in the hot sun and daubs him with honey, aiming to kill him via scaphism.

On 1 November 1964, producer Verity Lambert commissioned Whitaker to write a four-part historical serial to balance its science-fiction stories.

[4] Depictions of the sexual relationship between the siblings were cut from the script, partly as Hartnell found it unsuitable for the family show;[6] Glover was disappointed by their removal.

[5] Douglas Camfield was assigned to direct The Crusade, having worked as a production assistant on earlier serials An Unearthly Child (1963) and Marco Polo (1964) and proven himself a capable director of the third episode of Planet of Giants (1964).

[17] The establishing shot of a desert in the third episode was sourced from 9 feet (2.7 m) of silent 35mm stock footage supplied by the ABPC Film Exchange.

During recording of the final episode on 26 March, Lemkow injured himself with a knife, which went to a finger bone on his right hand; he was taken to hospital for a tetanus shot.

[19] Following the broadcasting of the second episode in April 1965, John Holmstrom of The New Statesman wrote that the show was failing, citing "the wooden charmlessness of the adventures".

[1] Following the serial's broadcast, Bill Edmund of Television Today directed praise at Glover's performance and Whitaker's writing, declaring "the dialogue and the story ... one of the best we have had in this series".

[1] Conversely, Television Mail wrote that "the appallingly flat dialogue of Dr Who could hardly be heard ... above the creaking of the plot", noting that the show should only be viewed "by people who have a profound contempt for children".

In The Discontinuity Guide (1995), writers Paul Cornell, Martin Day, and Keith Topping praised the ambition, imagination, and maturity of the storyline, noting that it "manages to avoid racism" but not misogyny.

[19] He praised the decision to split up the TARDIS crew and allow the viewer to see both sides of the Crusades, and lauded the guest cast, noting that "Walter Randall's El Akir is the most sinister character in the series to date".

[22] An audiobook of the novelisation, read by William Russell, was released by BBC Audio in November 2005 as part of the box set Doctor Who Travels in Time & Space, limited to 8000 copies.

[22] The serial was released in box set on VHS alongside The Space Museum by BBC Worldwide in June 1999, with postcards, a key ring, and a CD of the soundtrack; Russell performed linking material written by Stephen Cole and directed by Paul Vanezis at Ian Levine's house on 23 February 1999.