Americans remembering an old victory I guess, it was such a big shift in politics and economy. From a mechanical point of view I think the very early 15s are nice, and the later with stitch lever and potted motor is a peak in it's development. The European machines introduced right after WWII are intersting too, a lot of the brands came up with freearm zigzag models, aluminium body, Bernina, Elna Husqvarna, Anker, Adler. The technology soon incorporated various stitchpatterns, and by the 50s even double layer cam systems with stretchy stitches (Elna, Adler, Gritzner).