"I'd say that was about 15 inches," says B. Franklin Cooling, shoving his foot down the mouth of a very defunct 1864 Rodman gun, and eyeing the gap between the tip of his shoe and the roof of the gun. Cooling and I have reached the end of a long day trying to find Civil War forts, and this is the first gun we've seen. The gun, along with its 1865 partner, lies pretty much where Cooling, an instructor at the Army War College in Pennsylvania, first found it some 20 years ago -- on a forgotten site in Oxon Hill, Maryland, owned by the National Park Service. The guns served Fort Foote, one of the more than 150 forts and batteries erected by the Union to defend Washington during the Civil War. Foote was garrisoned until 1878. Then, although it was used as a military storage point and training ground off and on up to World War II, deterioration set in where the Union soldiers once drilled. Eventually, overgrowth hid the guns to all but a few of the intrepid like Cooling. "I knew the fort had to be back here somewhere," he recalls, "so I poked around and poked around. When I found it like this, it was . . . incredible." The place has an eerie quality to it -- big earthworks with their gun emplacements intact, crumbling masonry with funny, inexplicable holes, and the cobwebbed, rusty carriage for one of those evil-looking guns. In their day, the 49,000-pound guns themselves were enough to attract a stream of visitors, including Abraham Lincoln. It took 50 pounds of powder to fire one of their 500-pound balls, says a National Park Service publication, and an observer said the noise was such that the men standing by would "raise on their toes and open their mouths to lessen the effect." Now the guns are up on wooden supports built with "literally no money, from railroad ties we had in supply," says N.P.S. horticulturist Mel Poole, who brought in a crane last January to lift the guns off the ground. Chances of finding the funds to fully restore the earthworks are nil, says Poole, but that's not all bad. "After we freed the embankments of brush, kids started to drive their motorbikes up their sides. So you see, sometimes poverty is the best preserver." In 1861, at the outset of the war, Washington was protected only by one old river fort, Fort Washington. And that, says Lenard E. Brown of the National Park Service, "was garrisoned byCONTINUED ON PAGE 10. by one pensioner with a fondness for hard drink. It was generally believed that this bastion would have fallen for a bottle of whiskey." Earthworks were hurriedly thrown up in Arlington and Alexandria, and as both the war and the military bureaucracy progressed, a 34-mile defense system of forts, lunettes, redoubts and batteries emerged in a circle around the capital. The forts, placed roughly one-half mile apart generally followed the designs of Dennis H. Mahan, West Point professor to a generation of Civil War military men. The perimeters were wide parapets, 12-feet high, with room for a gun about every 30 feet. Inside was a magazine to store the powder, and "bombproofs" (bombshelters) to protect the garrison during heavy fire. Camped in back were the soldiers, who in many cases doubled as the construction crew. When they finished building the parapets, the soldiers dug wide ditches in front to deter the enemy; tangles of brush formed an "abatis" in front of the ditches, as a further deterrent. "Abatis" describes the snarl of overgrowth encumbering most of the forts today, and fort hunters are advised to go protected in prickle-proof pants and armed with a stout stick. They should also, Coolin more than a handful of Confederate soldiers. In July 1864, Fort Stevens was attacked by General Jubal Early. One story has it that General Early's troops were hopelessly deterred by the contents of Montgomery Blair's wine cellar in Silver Spring and lost the battle ("skirmish, really," says Cooling) due to inebriation. Another version says that Early's task was to divert Union troops from the attack on Petersburg -- a plan that appears to have worked. Casualties of the battle at Fort Stevens, 40 Union soldiers are buried at the National Battleground Cemetery on Georgia Avenue near Van Buren Street, "a little piece of solemn ground in the middle of the city," as Dr. Cooling describes it, "where you can weigh and measure the real cost of a war." The historian, a tall, thin native Washingtonian, spent his childhood near Forts Slocum and Stevens and played detective trying to find the rest. Using an 1871 report by the forts' creator, Major General John G. Barnard, Cooling spent 20 years tracking down remnants of old gun emplacements and batteries. Only a handful can still be traced, and even these are going fast. One appears to have bit the dust this April -- a particular loss to Hugo Botuccelli. Botuccelli is a full-time engineer and part- time Civil War buff who grew up in the shadow of Fort Totten (see the Metro station of the same name). Botuccelli and I spent a frustrating afternoon over a year ago looking for one of the more elusive forts, which he believed to be on the grounds of Catholic University. "It was named after the hero of Pensacola Harbor," he said, wandering about. "Adam Slemmer. Lieutenant, I think." He let me in on his theory: "I think it's across from Capuchin College. But don't print that." I mentioned the elusive fort to Cooling, who replied with glee that he knew "just where it is." He drove to the grounds of Marist College, run by Catholic Brothers in a pretty spot off Harewood Drive near Taylor Street NE. His face fell when he saw what had happened to the Brothers' ground. The bulldozer had come, and the shells of what will soon be apartments were going up beside the college. Something inside the good doctor mourned. Then he waded into the mud to see what the bulldozer had wrought in the way of relics. "Too deep," he said, sinking fast. "Too wet. "Maybe tomorrow." Tomorrow was too late for Fort Slemmer by about 40 years, according to Svain Ulvedal, construction overseer for the site. "Rumor had it that we were digging up an old Civil War fort," he admits, "but we didn't find a thing. The Brothers next door did some digging and had some good finds, but that was back in the 1930s. Things have changed." The chances of stumbling across a Civil War relic have long since passed for most, if not all, of these forts, and those who seek them do it more for a glimpse of history rather than a piece of it. The forts' importance to the history of this nation is hard to measure. "There are those who say that (Robert E.) Lee never had any intention of entering Washington or taking northern territory," Cooling said,"that the Union just gave this impression to its people...But of course, we can never know what was in Lee's mind -- there's always a bit of the unknowable in history." As the day was to prove, there's also a bit of the unfindable in Civil War fort- searching. We found some obvious ones -- Fort Reno, at the reservoir; Battery Jameson on the grounds of the Fort Lincoln Cemetery; Fort Dupont, in a corner of Fort Dupont Park. Many are obliterated, though local stores, apartments and schools in the area still carry their there's a shed near the Reno Reservoir like that." In 1930, the National Capital Parks started Fort Circle, described by them as "an interrupted greenbelt of open space land surrounding the inner city area of Washington, D.C., and Arlington County." In the District, 16 forts were converted into recreation areas by this act, though being part of Fort Circle is no guarantee of preservation. This is particularly sad, Cooling feels, in the case of forts east of the Anacostia River. "I call these the 'forgotten forts'," he said, as we drove down Alabama Avenue along a ridge that connected the Southeast forts almost down to Blue Plains. One of the "forgotten forts," Fort Stanton, is a lesson in frustration. An N.P.S. historian sent to do a study couldn't find the place, though he eventually located Fort Stanton Park. Not good enough, says Cooling. "Fort Stanton was somewhere back here," he said, driving to where the park backs up to Our Lady of Perpetual Help Church, "though I've never found anything worth finding around here." By this time, I was starting to see Civil War forts on every overgrown embankment and was ready to start looking on my own. The next day, our family took off down Chain Bridge Road in Virginia to search for Fort Marcy, thought to be somewhere near the intersection with the George Washington Parkway. No luck. Three days later, after a little research in Fairfax County's topographical maps, and a look into a privately published book by David V. Miller on Washington's defenses, we carefully measured the distance past Chain Bridge up the road, and stopped beside a chain link fence. Our kids were over the fence before we could satisfy the debate we had between propriety and curiosity, so we followed suit into a blackberry-strangled woods. Just a few yards in, we found it -- wide ditch, huge mound and, wonder of wonders, an old, vine-covered cannon. Much of the parapet is untraversable, but the dips that were gun emplacements are still very obvious, and inside the fort, we found a hole where (perhaps) the magazine had caved in. Then, as we chopped our way through the woods toward the hole, we discovered civilization: picnic tables, trash cans, mowed grass. Fort Marcy, it seems, is a park off a clearly marked exit fro' he saidm the northbound George Washington Parkway. So much for investigative work. To do your own sleuthing, Cooling recommends starting at either Fort Stevens or Fort Ward in Alexandria to get "a feel for what you're looking for." In the District, Cooling says that Fort DeRussey is in about the best shape next to Fort Stevens. But with a little poking around, an amateur can usually find a gun trench, a bit of parapet or a sign describing what once was on nearly all of the fort parks. Other forts, such as Fort Snyder on the grounds of St. Elizabeth's Hospital, require special permission for searching. On the Virginia side, the Arlington Line has been marked with signs by the Arlington County Cultural Heritage Commission. Fort Ethan Allen, next to the Madison County Community Center, has some good remains. In Alexandria, Fort Ward has been elaborately reconstructed, but few traces of other forts and batteries exist. Those hunting in Fairfax will have the biggest challenge; Fort Marcy is thought to be in the best shape. On the Maryland side downriver, the first fort -- Fort Washington -- is well preserved by the National Park Service. But Fort Foote, while lacking the tidy look of renovation, is well worth the search for those truly interested in the Civil War. Perhaps more than all the rest, it holds that haunWHERE THE FORTS ARE Here's a list of some of the better-preserved Civil War forts around Washington.

BATTERY JAMESON -- east of the Lincoln Statue in Fort Lincoln Cemetery.

FORT ETHAN ALLEN -- Glebe and Military Roads, next to Madison Community Center.

FORT DE RUSSEY -- North of Military Road in Rock Creek Park.

FORT DUPONT -- northeast corner of Massachusetts and Alabama Avenues.

FORT FOOTE -- six miles below Oxon Hill at the end of Fort Foote Road at the intersection with Jessica Drive.

FORT MARCY -- a half-mile north of Chain Bridge, reached by exit from northbound G.W. Parkway.

FORT RENO -- near the Reno Road Reservoir.

FORT SLEMMER -- behind Marist College at the site of "The Heights," Harewood Drive and Taylor Streets NE.

FORT SNYDER -- northwest of intersection of Alabama Avenue and 13th Street SE on grounds of St. Elizabeth's Hospital.

FORT STANTON -- north of Morris Drive to the rear of the Lady of Perpetual Hope Church.

FORT STEVENS -- Piney Branch Road and Quackenbos Street NW.

FORT WARD -- Braddock Road and North Howard Street in Alexandria.

FORT WASHINGTON -- Take South Capitol Street to Indian Head Highway. Four miles south of the Beltway on Indian Head Highway, turn right on Fort Washington Road.