In the early 1940s, Sentinel Comics was pumping out dozens of titles a month, with most of them ending up either on the newstands or in the hands of G.I.s, and for the latter group, it was clear that they were interested in three things: Cowboys, Legacy, and lady heroes who weren't afraid to show a little skin and kick a little butt.
One of their top-selling titles was The Flying Tigress, which featured the adventures of Mei Tran, a "Chinaman" who worked as secretary to an army general* in the Pacific Theatre. When she got wind of a predicament the Army couldn't solve, she'd put on a literal catsuit and solve it with her "kung fu magic." The comics were deeply, deeply racist and anti-Asian, but immensely popular, not the least because of her "exotic beauty." SC printed and distributed posters depicting Flying Tigress in costume, most of them going to soldiers overseas, and they were so sought after that there are reports of men getting into fist fights over them, and they're among the most valuable SC memorabilia of that time.
Meanwhile, over in Two-Fisted Comics, Detective Sweet moved from back-up feature to frontliner several times. By day, she's Esther Attar, a wealthy socialite and younger sister to a police detective who frequently finds himself in over his head, moving Esther to don a man's suit and gas mask and set out to solve the crime and save her brother, using perfume-based gadgets and gizmos to save the day. When she moved to a frontliner, the man's suit changed to a woman's cut and her popularity only increased.
Science fiction heroines and magical women were popular as well, with Lady Taara, Supreme Scientist Of Earth and Lady Lama being among the most popular.
As such, it was natural that Sentinel Comics would create a title that put all four ladies in the same comic. Utterly ignoring that Taara is from the 34th century and Flying Tigress is stationed out of Indonesia somewhere, the Lady Detectives comic featured the four female characters solving crime and fighting supervillains, and it should've been lightning in a bottle. It wasn't, though, and was cancelled after only ten issues.
Fans and academics have puzzled over why the title just didn't work, but the most common and simplest theory is this: it was just too cheesecake. As I said, the boys overseas wanted some sexy ladies, but they also wanted some buttkicking, and The Lady Detectives was just too light on action. It was also a half-mag, but they still insisted on putting a pin-up in every issue. The printing just wasn't good enough to sustain it, resulting in smeary, difficult to discern pin-up art. Most of the characters would vanish by the end of the war, never to return, although Lady Lama shows up in a more recent title and eagle-eyed readers have spotted a Flying Tigress poster in Unity's locker.
* The general's name and appearance varied wildly through the title. He starts as General Millcroft, an older man in a snappy uniform, then reappears as General Mills, a handsome middle-aged man, and in the later run of the comic has a decidedly Patton-like appearance and is generally called "General Willis," although in one memorable scene a character refers to him as "General Willis" while the nameplate on his desk clearly says "General Mills."
