"Balance of Terror" retells a World War II submarine movie set in deep space, resulting in an action story that is largely action-free. Beginning and ending in a chapel from the "happy privilege" wedding to a solitary (human) death delivering suspiciously coincidental drama, this episode serves primarily as an introduction to the Romulans and their war fought with Earth a century prior (that should have featured prominently in Archer's time and, of course, didn't). For all that this is an episode about those distant Vulcan cousins though we really don't learn much about their race except that they are creatures of duty (when not acting impulsively), and are cunning warriors (when not being out-ensorcelled).

For that matter we don't learn much about their technology either, except that they like birds, have perfected a cloaking device, and managed the trick of propelling sunstuff at hyperwarp speeds. Their plasma torpedo can easily devastate a deeply buried asteroid base (witness the anguished destruction of Outpost 4 and Commander Hansen) not to mention an exposed starship, yet in a tense moment they can also bring a Captain and his Yeoman intimately into each other's personal space. Scott reports the Romulan ship has simple impulse power but it's clear from the chase with Enterprise that some form of lightspeed drive is available. (Perhaps at best the ship can supply two out of three: warp, torpedo, or cloak.)

The best reason to watch this is the superb performance of Mark Lenard as the Romulan commander, a warrior wary of more war with these old enemies, who gets his wish to be destroyed before returning from his "glorious mission." Also featured are Lawrence Montaigne as the order defying, reduced two steps in rank Decius, and Paul Comi as the hot-blooded, bigoted Stiles (aka "S'Tiles").

The plot flops a bit, from being expendable initially to risking interstellar war violating the Neutral Zone. (The words 'balance' or 'terror' don't appear in the screenplay.) Also any production from so early in the series is likely riddled with anachronisms and incongruities, like phasers that look like photon torpedoes and books brought to meetings because Spock doesn't need them. But it also features one of the show's most illustrious lines, from McCoy to Kirk: "In this galaxy, there's a mathematical probability of three million Earth-type planets. And in all the universe, three million million galaxies like this. And in all of that, and perhaps more, only one of each of us." Too few to be wasted in war, no matter the ears.