Tales of Suspense #39 is what started it all. Tony Stark trips a booby trap while in Southeast Vietnam and is captured by Wong-Chu, a local marauder. Wong-Chu wants Stark to design a new weapon for him and instead, Stark builds (with the help of Professor Vinsen) his first Iron Man suit, which serves a dual purpose. It not only keeps him alive and prevents the shrapnel from the booby trap from reaching his heart but it also gives him the means to defeat Wong-Chu in hand to hand combat after Wong-Chu has his mercenaries gun down Professor Vinsen.
Iron Man’s first suit is a dull silver metal color and the dialogue is pretty funny because Stark/Iron Man explains what he’s doing to his opponents while he’s doing it. And he’s continually talking about the tiny “transistors” he uses to fuel all of Iron Man’s gadgets.