Before I begin, special thanks go to reader and commenter Michael for letting me know that these strips are on the DC website. I may never have found them otherwise. Thanks guy!
'The Most Deadly Weapon' (by Jerry Siegel and Joe Shuster): This story started in May 1939 and finished early in June, around the same time as Action Comics #13 and #14 were published. It starts intriguingly enough with Clark being sent to an inventor's house to witness a display of his new weapon, a gas which can penetrate any gas mask. I have serious doubts about this inventor, Adolphus Runyan - not only is his name Adolphus, but his demonstration consists of him gassing a monkey in a gas mask to death. The actual panel is heartbreaking. Just look at the poor little guy.
But karma is ever diligent, because crooks show up to murder him and steal the gas, with the intention of selling it to an arms dealer in war-torn Boravia. Superman follows them, and spends a good few strips just throwing bombs at buildings and tearing dirigibles in half with his bare hands. He retrieves the formula, watches as the arms dealer is killed by gas, stops the war, and as Clark Kent causes the arrests of the murderers. All in a day's work! This is really entertaining stuff.
This story is also the first time we get a name for Clark's editor at the Daily Star: George Taylor.