A SIMPLE stone slab marks the grave of Philadelphia gunsmith Henry Deringer, barely noticeable beneath a giant sycamore and the surrounding acres of intricate, towering tombstones in Laurel Hill Cemetery.

His name is mostly forgotten here, his workshops in Northern Liberties paved over for progress or pulled down by time, just empty lots with broken glass and weeds. No murals, statues or buildings bear his name here and no one's ever asked the commonwealth to stake a blue historical marker along North Front Street for the man who ushered in the era of "concealed carry," whose name became a noun, like Jell-O or Kleenex, still used today to describe any compact, easy-to-hide handgun that's deadly at close range.

"Deringer, like 'Shrapnel,' conveyed no other meaning in English," author J.E. Parsons wrote in Henry Deringer's Pocket Pistol, the only book written about the Easton-born son of German settlers.

Deringer followed his father into the business and was one of the last American gunsmiths to make weapons by hand, producing thousands of pairs of the "death-dealing little cannons" - as one writer of Westerns described the design - in Philadelphia in the early to mid-1800s.

The most significant monument is a morbid one: a single-shot, muzzle-loading pistol with a black walnut stock inlaid with silver that changed America forever. That gun sits in a glass case inside Ford's Theatre in Washington, D.C., recovered from the state box there after John Wilkes Booth used it to shoot President Abraham Lincoln in the back of the head on the night of April 14, 1865. If you move in close to the display and squint, you can read the words "Deringer Philadel" etched into the stock.

Deringer was still making the guns in 1865, but they already had been wildly popular with civilians for decades, his biggest market being California during the Gold Rush. Deringer couldn't keep up with the demand for his pistols as settlers pushed west, out into the unknown, fearful of Native Americans, card sharks, rustlers and most often one another.

"Deringer didn't have to advertise," Parsons wrote.

Deringers were marketed for "personal protection," at a time when most weapons were primarily for soldiers, hunters or the homestead. Before the Deringer, concealable weapons still were bulky, liable to catch on fabric when they were needed or to burn a hole in someone's pants.

Everyone from politicians to prostitutes wanted a single-shot Deringer to tuck away in their waistbands for emergencies, or to plant a little fear in any would-be thug. Many saloons and towns in the west would enforce "No Weapons" policies that never fully applied to the Deringer.

"Everybody had to have a gun, and with a Deringer nobody knew whether or not you had one," said author and gun historian R.L. Wilson of Reno, Nev. "If you were in a place that you needed to have a gun and didn't have one, you're a dead man."

Well before the Lincoln assassination, Deringers were regularly mentioned in newspaper articles about high-profile murders. In 1855, a San Francisco gambler used a Deringer to gun down a U.S. Marshal also armed with a Deringer. A year later, the editor of the San Francisco Bulletin was shot by a city supervisor with a Deringer. In 1859, across the street from the White House, U.S. Rep. Daniel Edgar Sickles, of New York, fatally shot Philip Barton Key II, the district attorney of the District of Columbia, with a Deringer after he learned that Key was having an affair with his wife.

"In their day and age, they were simply the most effective arms available," Parsons wrote in his book.

Plenty of copycats

The popularity of Deringer's design triggered a veritable Wild West of copycats, mostly made by former employees in Philadelphia who went off on their own. Deringer had a wide-ranging network of distributors, including Tiffany, and he sent agents to New York to search for counterfeits, offering $100 rewards for any evidence, according to Parsons.

Deringer filed a lawsuit against some former employees for using his name and design. That case, which Deringer won after his death in 1868, became a landmark in trademark law, but he had long since lost control of his name as a catchall for any small, concealable gun.

Some designers simply tweaked the design; another actually recruited a tailor named J. Deringer and got permission to stamp his name on a gun stock. Many gunsmiths simply added an "r" and that spelling, Derringer, stuck through time whenever the weapon is mentioned. Deringer's heirs kept making guns, but his company no longer exists.

"The legacy lives still on. They were needed back then and they are needed today," said Elizabeth "Lady Derringer" Saunders, owner of American Derringer, a Texas-based manufacturer of modern variations on Deringer's pistol.

A city of gunsmiths

Gun historians say that Philadelphia was a major center for gunmaking during Deringer's era, with hundreds of gunsmiths, including Edward K. Tryon, John Krider and J. Henry & Sons. There was a major market for military-grade rifles for the War of 1812 and later for use by Native Americans, and for the growing fur trade and expansion into the West. Deringer supplied thousands of rifles for the War of 1812 and conflicts with Mexico before focusing most of his attention on the pocket pistols.

"From the 1820s to 1880s, Philadelphia was one of the centers in the country for the best target guns and shotguns anywhere," said Ronald Gabel, a gun collector and historian who is writing a book about Philadelphia gunsmiths.

Deringer was considered a "well-to-do" member of Philadelphia society, said gun historian Lewis Southard. He owned several pieces of real estate in the region and coal-mining tracts in Luzerne County. His obituary in the Evening Bulletin said that he was "one of the oldest, most influential and respected of Philadelphia's native citizens."

The Industrial Revolution helped hasten the end of major gun manufacturing in Philadelphia, as Samuel Colt, in Connecticut, and the Springfield Armory, in Massachusetts, began to mass-produce rifles and revolvers. Colt sold almost 10,000 of its own Derringers in England alone, according to Parsons, and just about every gun manufacturer in the world made some variation of the gun.

In 2009, the Remington Double Derringer found in the sock of infamous gangster John Dillinger when he was fatally shot sold for $95,000, and they're still made today by companies including American Derringer and Bond Arms. An Italian gunmaker, Davide Pedersoli, makes a replica of the original Deringer.

Many states have tight restrictions on modern Derringers, particularly California, where the original Deringer was so popular and deadly. Only a couple of gun manufacturers remain in Pennsylvania, and just a handful of shops sell guns in Philadelphia.

In a city plagued for decades by gun violence, it's doubtful that anyone's going to push for Deringer to be memorialized beyond his simple grave marker. But the little gun he hammered out by the thousands in Northern Liberties changed the nature of handguns in America with a small, simple design.

"If you took the top 10 gunmakers of his time, he was up there," Wilson said. "He was a very smart gunmaker, and his guns were beautiful little things to behold."