In that year, the Earth Outposts guarding the Neutral Zone came under attack by a Romulan Bird-of-Prey, equipped with a new, advanced cloaking device, and powerful plasma-based weaponry, whose crew was on a mission to test the resolve of Earth force after a century of nonexistent contact with Humans. The attack resulted in massive damage and casualties, including the deaths of Hansen's weapons crew. Hansen was subsequently contacted by Captain Kirk aboard the USS Enterprise, who was attempting to intercept the enemy vessel before it could attack again. After giving a report on the attack to Kirk, Hansen was killed when Outpost 4 was destroyed in a final attack by the Romulans. (TOS: "Balance of Terror")
Commander Hansen, played by Garry Walberg, wore a uniform that varied from the crew of Enterprise, but featured no rank insignia on the sleeves. It featured a semicircular assignment patch (denoting he served at an outpost) rather than the familiar Enterprise arrowhead. The uniform was made of a shinier fabric, and the color was dull, closer to beige than the mustard yellow velor used for the ship's costume. Beige was not seen in concurrent Enterprise uniforms, but had been used in the previous uniform style to represent the operations division, before that division's color was changed back to red. This costume appeared again (patch and all), on another outpost attack victim, Lieutenant Harold of Cestus III in TOS: "Arena". The seashell-like assignment patch also appeared again as a decoration of the mirror universe uniform worn by Dr. McCoy in TOS: "Mirror, Mirror".
Since there were no rank insignia shown on the uniform cuffs, it is possible that Hansen was a commander by position only, and not by grade.