Victory's EPs 1, 3, and 16 highlighted the conflict with Germany's U-boats in the Atlantic. Not until EP21 is there any coverage of America's offensive submarine missions, primarily in the Pacific. We begin with the construction of US subs and the training of their crews on America's east coast. Next, one new submarine takes its maiden voyage, headed to the western Pacific to sink the merchant ships that sustain Japan's home islands.

Musically, EP21 might compare to EP15's D-Day: a modest new theme is treated to a full-episode elaboration—in this case, Bennett's own. But he doesn't first give his melody a complete presentation; rather, he reverses the pattern by first offering snippets of the tune and withholding a full exposition until 2:28. For convenience this new one-strain march is labeled “M-21” here in this chapter; it's shown at 3:01–3:31 [A] in its most straightforward exposition.

EP21 opens with the schooling of Navy sub crews at New London, Connecticut: “No training is more rigid, no training is more intense, than that of the submariner who must fight his battles imprisoned in a carcass of steel sailing in the deeps of the world's water basins.” The angular bass melody at 1:05 [B], which will become the ending of the new M-21 march, is followed by more subdued music at 1:19 [C], developed from M-21's first two bars. Footage of the sailors’ tutelage includes both classroom study and underwater practice at deep-sea evacuation. At 2:21 the scene shifts to Atlantic seaboard submarine construction and christening. M-21 is introduced by its final four bars [D] and then the full strain itself in D flat [E] at 2:28 and in F at 3:01—already shown as [A]: “On the New England coast, the killer fish are spawned that will eat at the vitals of Japan.”

In EP21 the new march is never absent for long, and bits of M-21 return at 3:51. We next follow a new sub and its fresh crew cruising down America's east coast in relative safety: “From New England to Hawaii, from Point Judith to Diamond Head, the eight officers and 75 men in each new submarine learn to live with their boat and with each other, conditioning themselves for the tests and trials that are yet to come.” The mood is relaxed at 4:11 [F]; again, the M-21 tune is used, in trumpet and cellos.