The American-English expression skirt patrol, which denotes a search for female companionship, originated in army slang during the Second World War.

The earliest occurrences that I have found are as follows, in chronological order:

1-: From an article originally published in Collier’s, and reprinted in several U.S. newspapers in April 1941—for example in The Amarillo Globe (Amarillo, Texas) of Tuesday the 8^th:

New slang is coming out of Lowry Field, fast-growing home of the bombardment, photographic and clerical schools of the Army Air Corps at Denver. Sample dialog: “Where ya goin’ in your swanks?” “Skirt patrol; wanna go?” “Can’t. I’m no bog-pocket but Uncle Sam’s party ain’t till tomorrow. Besides, I’m bubble-dancin’ today.” Translated: “Swanks” are best clothes; “skirt patrol” is a hunt for female companionship; “bog-pocket” is a tightwad; “Uncle Sam’s party” is payday; “bubble-dancing” is dishwashing. Drinks are “serum.” When a soldier downs enough serum he “starts to spoil” until he becomes “swamped” or “draped.” If he behaves himself he “keeps dainty.” When something pleases him it’s “side meat” or “strictly cut plug.” If it pleases him mightily it’s “hydraulic” or “with onion”—even if it’s a girl.

2-: From the Milwaukee Sentinel (Milwaukee, Wisconsin) of Monday 12^th May 1941:

Some Aid to English Is Army Men’s Need
Folks at Home Would Find Hard Time Translating Talk of Boys in Uncle Sam’s Service

When a foot slogger is on skirt patrol with plenty of soft money on Uncle Sam’s party, isn’t that strictly cut plug?
A yard bird’s hitch isn’t all steam shoveling. Of course, if you get swamped, the skipper might throw the book for some bubble dancing or bad time.
But you get used to it.
You even get used to this type of jargon, taken from a “glossary of common military expressions and slang” recently issued by the U.S. army and received by WISN to be used as a guide in preparing dramatic programs.
AND HERE’S ANSWER
Just in case you need an interpreter when Johnny gets back from his year of service, we’ll translate:
When an infantryman is searching for feminine companionship with a pocket full of currency on pay day, isn’t that a grand and glorious feeling?
A recruit’s life isn’t all potato peeling. Of course, if you get intoxicated the company commander might give you dish washing or time in the guard house.
It isn’t what you were taught in school, but climb on the wagon, mister, this is how they talk. Should Johnny order blackstrap, side arms and punk with his buzzard meat, you’ll know he wants coffee, cream, sugar and bread with a chicken dinner.
HERE’S NEXT LESSON
That was easy, wasn’t it? Now for the next lesson.
There are all types of personalities around an army camp. A good man to know is a shack rat—according to the army glossary, a “garrison soldier who has made a friend in the city and usually goes to town every night.”
Then there are the bog-pockets. They’re tightwads who leave you with the tariff on the serum—the check for the drinks, in other words.
When a freshman is blue, he’ll be cheered up immensely with a sugar report or a little duff—a letter from home or some candy.
It’s a little hard to follow sometimes. A commissary officer is known as beans, and beans are known as stars and stripes.
Chow may consist of java, cow juice and canned willie, which needs no translation.
The effect of the demon rum is listed most often in the army glossary. Intoxication is variously defined as “starting to spoil,” “swacked,” “swamped” and “draped.”
The air corps has its own distinctive patrols. Randolph Field, Tex., the “West Point of the air,” is known to fliers as the “country club.” “Cadet widows” is a name applied to a “young lady who has known flying cadets for many years.” The “biscuit gun” is an imaginary cannon to shoot food up to fledgling fliers who have difficulty bringing their planes back to the field. “Bird dogging” is that unforgivable errer [sic] when a dodo, or lower classman, dances with an upper classman’s date.
CLIP THIS LIST
Clip this additional list for your next letter to camp:
Army banjo—a shovel
Canned horse—corned beef
Coffee cooler—one who likes easy jobs
Cousin—the girl friend
Dog tags—identification disks
Dry run—maneuvers
First grader—master sergeant

3-: From the Pittsburgh Post-Gazette (Pittsburgh, Pennsylvania) of Tuesday 20^th May 1941:

Push Button Pick-Ups: Tex Howard has compiled a glossary of picturesque army slang for KQV’s We’re in the Army Now series. . . . Some of the expressions are: “Bubble dancing”—meaning dish washing; “draped”—drunk; “stars and stripes”—beans; “skirt patrol”—looking for female companionship; “yard bird”—raw recruit; “mitt flopper”—one who does favors for his superiors; “canned Willie”—corned beef; “diddie bag”—where a soldier keeps his valuables.

4-: From the Tulsa Daily World (Tulsa, Oklahoma) of Friday 23^rd May 1941:

Uncle Sam’s Strict On His Army Girls
‘Skirt Patrol’ Wants Fluff, Not Uniforms

With so many eligible “dates” in training camps all over the country, many a pretty young miss will have to learn a new code of deportment if she wants to endear herself to the boys working for Uncle Sam.
With this in mind Henrietta Ripperger has summed up several worth-while hints; if followed, they will make you a welcome visitor to military posts. Here they are:
Don’t show up with chevrons on your jacket, stripes on your sleeves, sailor collars with emblems. The boys have to look at braid and eagles all day long. They want you in fluff, not in uniform.
Don’t say you can’t hoof it in the shoes you have on. Wear sports or spectator-sports shoes, or make up your mind to be a sport and suffer. The service walks.
Don’t try to get special privileges. Don’t use influence or try to vamp the sergeant. Your guy will suffer for it later on.
Don’t expect the army to feed you. Learn to live on sodas and like it.
Don’t yoo-hoo at the general even if he is your dad’s best friend. Wait until the general yoo-hoos at you!
Don’t be chummy with privates if you’re out with a brass hat.
Don’t run about like a child star bringing her parents together in a movie, coyly introducing privates to officers.
Don’t make yourself conspicuous. You might be “posted,” which means you’re not allowed to come again.
Don’t make it hard for your man to report for duty. Don’t smuggle him anything to drink. Asked as to the effect of alcohol, an Annapolis man wrote, “The effect on a midshipman is usually a complete change of residence and occupation.”
Learn to smile when you say good-bye, and the skirt patrol will be back for you next time.