 | John Gregson | ... | Capt. Bell, HMS Exeter |
 | Anthony Quayle | ... | Cdre. Harwood, HMS Ajax |
 | Ian Hunter | ... | Capt. Woodhouse, HMS Ajax |

| Jack Gwillim | ... | Capt. Parry, HMNZS Achilles |
 | Bernard Lee | ... | Capt. Dove, MS Africa Shell |
 | Lionel Murton | ... | Mike Fowler, Montevideo |
 | Anthony Bushell | ... | Millington Drake, British Minister, Uruguay |
 | Peter Illing | ... | Dr. Guani, Uruguayan Foreign Minister |

| Michael Goodliffe | ... | Capt. McCall, R.N., British Naval Attache, Buenos Aires |
 | Patrick Macnee | ... | Lt. Cmdr. Medley, HMS Ajax |
 | John Chandos | ... | Dr. Langmann, German Minister, Uruguay |
 | Douglas Wilmer | ... | M. Desmoulins, French Minister, Uruguay |
 | William Squire | ... | Ray Martin, Montevideo |
 | Roger Delgado | ... | Capt. Varela, Uruguyan Navy |
 | Andrew Cruickshank | ... | Capt. Stubbs, Doric Star |

| Christopher Lee | ... | Manolo |
 | Edward Atienza | ... | Pop |
 | April Olrich | ... | Dolores |

| Peter Finch | ... | Capt. Langsdorff, Admiral Graff Spee |
 | María Mercedes | ... | Madame X (credit only) |

| John Schlesinger | ... | Prisoner on Graf Spee |
 | John Le Mesurier | ... | Rev. George Groves, Padre, HMS Exeter |
| rest of cast listed alphabetically: |
 | David Farrar | ... | Narrator |
 | John Merivale | ... | Cowburn, Pilot, HMNZS Achilles |
 | Douglas Argent | ... | Sub. Lieutenant, HMS Ajax (uncredited) |
 | Vincent Ball | ... | Barnes, HMNZS Achilles (uncredited) |
 | Ken Barker | ... | Marine Officer / HMS Ajax (uncredited) |
 | Michael Barnes | ... | Midshipman, HMS Ajax (uncredited) |
 | Raymond Barrie | ... | Shirley, HMNZS Achilles (uncredited) |
 | Terence Bayler | ... | Stoker, HMNZS Achilles (uncredited) |
 | Alan Beale | ... | Capt. Pttinger, prisoner on Graf Spee (uncredited) |
 | Richard Beale | ... | Captain Pottinger (uncredited) |
 | David Benson | ... | Marine Officer, HMS Ajax (uncredited) |
 | John Britton | ... | Navigator, HMS Ajax (uncredited) |
 | Robert Bruce | ... | Lt. Cmdr. Smith, HMS Exeter (uncredited) |
 | Anna Burden | ... | Madame Desmoulins, Montevideo (uncredited) |
 | Richard Burrell | ... | Navigator (HMS Exeter) (uncredited) |
 | Tony Burton | ... | Young Sailor, Aft-conning, HMS Exeter (uncredited) |
 | David Cameron | ... | Pilot Officer Lewin, pilot, spotter plane, HMS Ajax (uncredited) |
 | Alan Casley | ... | Rating, Aft-conning, HMS Exeter (uncredited) |
 | Ronald Clarke | ... | Prisoner on Graf Spee (uncredited) |
 | Michael Collins | ... | Chief Yeoman, HMS Ajax (uncredited) |
 | James Copeland | ... | Chief Yeoman, HMNZS Achilles (uncredited) |
 | Tita Dane | ... | (uncredited) |
 | Gron Davies | ... | Chief Engineer, Trevannionion, prisoner on Graf Spee (uncredited) |
 | Denton De Gray | ... | Observer Kearney, Spotter plane, HMS Ajax (uncredited) |
 | Maxwell Denne | ... | Petty Officer, HMNZS Achilles (uncredited) |
 | Captain Patrick Dove | ... | Capt., Streonshalh, prisoner on Graf Spee (uncredited) |
 | Peter Dyneley | ... | Captain, Newton Beach, prisoner on Graf Spee (uncredited) |
 | Eynon Evans | ... | Chief Engineer, Newton Beach, prisoner on Graf Spee (uncredited) |
 | Jack Faint | ... | Chief Officer, Ashlea, prisoner on Graf Spee (uncredited) |
 | Peter Fontaine | ... | Gunnery Officer, HMS Ajax (uncredited) |
 | John Forbes-Robertson | ... | Lt. McBarnett, HMS Exeter (uncredited) |
 | Frank Forsyth | ... | Petty Officer, Bridge, HMS Ajax (uncredited) |
 | Barry Foster | ... | Bill Roper, Capt. Bell's messenger, HMS Exeter (uncredited) |
 | Colin Free | ... | 2nd Messenger, HMS Ajax (uncredited) |
 | Richard George | ... | Chief Officer, Trevannion, prisoner on Graf Spee (uncredited) |
 | Keith Grieve | ... | Sick Bay P.O., HMNZS Achilles (uncredited) |
 | Lucia Guillon | ... | Telephone Girl, Montevideo (uncredited) |
 | Peter Halliday | ... | Guani's Secretary, Montevideo (uncredited) |
 | Ken Hayward | ... | Spotting Officer, Gunnery Control, HMS Exeter (uncredited) |
 | Patrick Horgan | ... | Signalman, HMNZS Achilles (uncredited) |
 | Helen Horton | ... | (uncredited) |
 | Mary Jones | ... | Miss Shaw, Millington Drake's secretary (uncredited) |
 | Kerry Jordan | ... | O.S. Rogers, HMNZS Achilles (uncredited) |
 | Patrick Jordan | ... | Signalman, Aft-conning, HMS Exeter (uncredited) |
 | Marvin Kane | ... | (uncredited) |
 | Howard Lang | ... | 'Guns', HMS Exeter (uncredited) |
 | Frank Lloyd | ... | Messenger, HMNZS Achilles (uncredited) |
 | Cyril Luckham | ... | Lt. Jasper Abbot, HMNZS Achilles (uncredited) |
 | Kenneth Luckman | ... | Mess P.O., HMNZS Achilles (uncredited) |
 | Ivor Mairants | ... | Guitarist accompanying Dolores in Montevideo (uncredited) |
 | Alan Masterson | ... | Midshipman, HMS Exeter (uncredited) |
 | Jack Mayne | ... | (uncredited) |
 | Lane Meddick | ... | P.O. Stacey, HMNZS Achilles (uncredited) |
 | John Merrivale | ... | Cowburn, HMNZS Achilles (uncredited) |
 | Kenneth Midwood | ... | Petty Officer, Gunnery Control, HMS Exeter (uncredited) |
 | Donald Moffat | ... | Swanston, Look Out, HMS Ajax (uncredited) |
 | George Murcell | ... | Chief Officer, Newton Beach (uncredited) |
 | Anthony Newley | ... | Radio Operator, Tairoa, prisoner on Graf Spee (uncredited) |
 | Joseph O'Conner | ... | Chief Engineer, Doric Star, prisoner on Graf Spee (uncredited) |
 | David Paltenghi | ... | Customs Officer, Montevideo (uncredited) |
 | Conrad Phillips | ... | Lt. Washbourne, Gunnery Officer, HMS Achilles (uncredited) |
 | Ambrosine Phillpotts | ... | Mrs. Millington-Drake, Montevideo (uncredited) |
 | Columba Powell | ... | Lost child in crowd (uncredited) |
 | Edward Powell | ... | Chief Officer, Huntsman, prisoner on Graf Spree (uncredited) |
 | Irene Prador | ... | (uncredited) |
 | Peter Prowse | ... | Look Out, HMS Exeter (uncredited) |
 | Roy Purcell | ... | Duty Officer Pennefeather, HMS Ajax (uncredited) |
 | Rive Rola | ... | (uncredited) |
 | Alan Rolfe | ... | Petty Officer, HMS Exeter (uncredited) |
 | David Rose | ... | Boy Dorset, HMNZS Achilles (uncredited) |

| Peter Scott | ... | 1st Messenger, HMS Ajax (uncredited) |
 | Peter Smallwood | ... | Spotting Officer, HMS Ajax (uncredited) |
 | Muriel Smith | ... | Dolores, Montevideo (uncredited) (singing voice) |
 | Julian Somers | ... | Quartermaster on Graf Spee (uncredited) |
 | Barry Steele | ... | Midshipman, HMS Ajax (uncredited) |
 | Graham Stewart | ... | Signalman, HMS Exeter (uncredited) |
 | Nigel Stock | ... | Chief Officer, Tairoa, prisoner on Graf Spee (uncredited) |
 | Alan Townsend | ... | Duty Officer, HMS Ajax (uncredited) |
 | Guy Verney | ... | Cmdr. Graham, HMS Exeter (uncredited) |
 | Tony Wager | ... | Look Out, HMS Ajax (uncredited) |
 | Colin Wall | ... | Boy Bugler, HMS Exeter (uncredited) |
 | John Warren | ... | Chief Yeoman Signals, HMS Exeter (uncredited) |
 | Patrick Westwood | ... | Archer, HMS Ajax (uncredited) |
 | George Whiting | ... | Chief Engineer, Aft-conning, HMS Exeter (uncredited) |
 | Ian Whittaker | ... | Messenger, Boiler Room, HMNZS Achilles (uncredited) |
 | David Williams | ... | Look Out, HMS Exeter (uncredited) |
 | Neil Wilson | ... | Mess P.O., HMNZS Achilles (uncredited) |
 | Brian Worth | ... | Radio Operator, Doric Star, prisoner on Graf Spee (uncredited) |