How did Harriet Tubman lead so many slaves to freedom on the Underground Railroad? With careful planning, plenty of luck, and a little opium.

“I never run my train off the track, and I never lost a passenger”—so boasted Harriet Tubman, the most successful conductor on the Underground Railroad. Tubman ran up her unblemished record while leading groups of runaways on a 650-mile odyssey from eastern Maryland to St. Catharines, Ontario. Starting in 1850, Tubman made a total of 19 journeys, personally freeing more than 300 slaves. The rewards offered for her capture totaled an astronomical $40,000 (just over $1 million in today’s money), but the bounties went unpaid.

So how exactly did she score that perfect record? Here are some tips based on her harrowing adventures—call it the Tubman Technique.

KNOW THE TERRAIN; MOVE BY NIGHT: Many slaves had never ventured far from their owners’ property. Slave owners deliberately kept them close so they wouldn’t know how to escape. As a result, runaways needed Tubman to do the navigating. She led groups along dirt roads and paths by night. If no safe house was available during the day, Tubman hid her passengers in dense forests, swamps, or other places no one would think to look. When it was safer to split up—a decision she sometimes made when she knew the group was being hunted—Tubman gave simple, easy-to-follow advice for reaching a meeting point, like “follow the drinking gourd” (the Big Dipper, which points north).

MAKE SURE EVERYONE KNOWS WHO’S IN CHARGE: With runaway slaves facing draconian punishments if they were caught, it’s no surprise that Tubman’s passengers occasionally changed their minds and wanted to return to servitude. But Tubman would have none of it—letting fugitives go back to their old homes risked exposing her entire network. When faced with timorous souls, Tubman would brandish her gun and offer them a simple choice: “You’ll be free or die a slave!”

KNOW YOUR LIMITS: Although there were thousands of slaves waiting to be freed, Tubman never bit off more than she could chew. Since large numbers would inevitably attract more attention, she usually conducted runaways in groups of 12 to 15—the most that could safely take cover in an out-of-the-way barn, cellar, or ditch.

DRUG THE KIDS: Since Tubman always tried to keep families together, her traveling parties often included small children who could slow the group down or, worse, give it away by crying at the wrong moment. To curb these problems, Tubman always carried paregoric, an opium tincture that could knock out tots for hours at a time.

WORK THE NEWS CYCLE: Slave owners often ran newspaper ads to alert bounty hunters and law enforcement about substantial rewards for capturing runaway slaves. So Tubman timed her rescues to begin on Saturdays—giving her passengers a 48-hour head start before masters could run ads in the Monday papers.

GET GOOD INTEL: During the Civil War Tubman ramped up her activities through a partnership with the Union Army, which freed slaves to weaken the Confederate economy. On June 1, 1863, Union officers provided 150 black soldiers for a Tubman-masterminded raid on rice plantations along the Combahee River in South Carolina. Tubman used an elaborate network of spies among the slave population to gather detailed intelligence about Confederate defenses, including the location of floating mines in the river. The raid freed around 750 slaves.

WHEN ALL ELSE FAILS, TRY BRIBERY: Underground Railroad conductors were no strangers to “greasing the wheels” by paying off corrupt officials and ordinary citizens. Tubman found bribes especially effective at the Canadian border, where officials could be persuaded to turn a blind eye to “visitors” who clearly weren’t tourists. The bankroll for bribes came from supporters, both white and black, called “stockholders” in railroad lingo.

DON’T BE AFRAID TO USE LIVESTOCK: Tubman’s greatest strength was her ability to think on her feet—but her use of strategic poultry didn’t hurt, either. When a route forced her to pass through her own former master’s hometown, Tubman disguised herself as an old woman and bought two chickens, carrying one under each arm to complete the disguise of a domestic slave fetching dinner. When she spotted her former master approaching in the street, Tubman “lost” the chickens and went scrambling after them, to the amusement of her master and the other white townsfolk—thus allowing her to make a quick escape.

This article originally appeared in mental_floss magazine, available wherever brilliant/lots of magazines are sold. Get a free issue here!