Star Trek (1966–1969)
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Balance of Terror 

The Enterprise must decide on its response when a Romulan ship makes a destructively hostile armed probe of Federation territory.



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Episode complete credited cast:
Paul Comi ...
Lt. Robert Tomlinson
Barbara Baldavin ...
Garry Walberg ...
Commander Hansen
John Warburton ...
The Centurion


The Enterprise answers a distress call from Federation Outpost #4, a monitoring station on the Federation side of the neutral zone with the Romulan Empire. The outposts were established over a century ago and no one has actually seen a Romulan. The Romulan vessel seems to have some type of high energy explosive device as well as a cloaking device to make the ship invisible. When it appears that Romulans bear a strong resemblance to Vulcans, Kirk must deal with a rebellious crew member. He must also engage in a dangerous cat and mouse game with a very intelligent Romulan commander. Written by garykmcd

Plot Summary | Plot Synopsis


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Release Date:

15 December 1966 (USA)  »

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Technical Specs


Sound Mix:


Aspect Ratio:

1.33 : 1
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Did You Know?


Dialogue in the episode establishes that there are multiple weapons batteries on board, with "helm" and "starboard" weapons being specifically mentioned. See more »


The Enterprise first glimpses the Romulan ship via Outpost #4's view screen. Yet, after Outpost 4 is destroyed, the Romulan ship is still visible. See more »


Mr. Spock: [holding a shell of metal] From the outpost protective shield - cast rodidium. This is the hardest substance known to our science.
[With hand pressure alone, the fragment shatters]
See more »


Featured in Pioneers of Television: Science Fiction (2011) See more »

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User Reviews

"The Enemy Below"
2 June 2009 | by (The San Francisco Bay Area) – See all my reviews

Nearly ten years before Desilu Studios chanced Star Trek, Robert Mitchum and Curt Jurgens were up on the big screen showing the progenitor to one of Star Trek's more famous episodes in the form of a US Navy DDE (destroyer escort) matching wits with a German U-boat in the South Atlantic. This observation was not my own, but made by a good friend who works for another man that publishes a game based on the classic Star Trek franchise.

Classic Roman society is used as a template for Vulcan cousins, and are assigned a nationalistic and expansionist philosophy, again not unlike Nazi Germany post the Imperial regime from which the Kaiser abdicated power after the first world war.

The episode brings a flavor of the classic U-Boat sub hunt to the science fiction audience, and, remarkably, uses a then recently declassified (and still experimental) technology developed by the USAF; the cloaking device. The idea was to mask bombers (notably the B-51 Hustler if I recall correctly... which I may not) as they drove deep into enemy territory to deliver their payload. It was an airborne mimicry of the submarine concept. It's technical details are too lengthy and esoteric to place in this post (that, and I don't recall all of them now :-)), but the concept, down to its actual name, was used in this episode. And, if memory serves, in Lucas's "The Empire Strikes Back" in a throw away line just after the asteroid chase sequence.

The episode, like the movie upon which it borrows, is rife with tension. One mind is pitted against another in a struggle for life and death. Each is duty bound to vanquish the other. They must act upon their orders to ensure their sides victory. Unlike the feature film, Trek's "Balance of Terror" has a definitive victor. I'll let you guess who it is ;-) But there's more than just a simple WW2 tale put into space operating here. Note the title. Note the period in which this episode and show were made; the Cold War. Marry the two, and keep in mind the various proxy wars both US and USSR waged across the globe, and you'll start to see the larger theme.

Yet, with all this high mindedness, with all the military tactical tension, there are personal costs on both sides. It's not the primary focus of both film and episode, but a reminder of the cost of such conflict among fellow living creatures.

Definitely worth seeing again.


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