Currently available on 2 streaming services.

The Citadel streaming: where to watch online?

You can buy "The Citadel" on Apple TV, Amazon Video as download or rent it on Apple TV, Amazon Video online.

Cast

Robert Donat
Dr. Andrew Manson
Rosalind Russell
Christine Manson
Ralph Richardson
Dr. Philip Denny
Rex Harrison
Dr. Frederick Lawford
Emlyn Williams
Owen
Penelope Dudley-Ward
Toppy LeRoy
Francis L. Sullivan
Ben Chenkin
Mary Clare
Mrs. Orlando
Cecil Parker
Dr. Charles Every
Nora Swinburne
Mrs. Thornton
Edward Chapman
Joe Morgan
Athene Seyler
Lady Raebank
Felix Aylmer
Mr. Boon
Joyce Bland
Nurse Sharp
Percy Parsons
Mr. Stillman
Dilys Davies
Mrs. Page
Basil Gill
Doctor Page
Joss Ambler
Dr. A.H. Llewellyn
Cameron Hall
Man Who Buys Microscope (uncredited)
Bryan Herbert
Husband Whose Wife Has Typhoid (uncredited)
David Keir
Mr. Wickes (uncredited)
Joan Kemp-Welch
Nurse Assisting at Childbirth (uncredited)
Eliot Makeham
Jack the Pharmacist (uncredited)
Elliott Mason
District Nurse (uncredited)
Gus McNaughton
Tom Evans (uncredited)
Bernard Miles
Medical Aid Society Committee Member (uncredited)
Leslie Phillips
Girl (uncredited)
Kynaston Reeves
Doctor (uncredited)
Harry Terry
Miner (uncredited)
Ben Williams
Evan Lewis (uncredited)
D.J. Williams
Old Thomas (uncredited)