Sollie O'Berry and Lizzie Howell O'Berry were both born in  the SETTLEMENT of Fort Dade "near" Mt. Zion Cemetery.  William Staten Jackson, Matthew E. Jones, John Howell and several of the earliest pioneers of Blanton settled there.

Marker on 17th Street in Dade City

(Very interesting! The original Ft. Dade was really on the Withlacoochee River.)

Frank Laumer traces the history of the several "Fort Dades".
Here is documentation for locations in Pasco County:

"....But it was all down hill. After the fitful struggle with the Seminoles ended in 1842, the troops remained for shorter and shorter periods. Then some years were skipped entirely, until in September 1849, Lieutenant Colonel Henry Bainbridge with
a detachment of the Seventh Infantry sent up from Fort Brooke to garrison the fort, stopped eight miles short of the river where old Fort Dade waited. 27
Here along the military road a few settlers had put up shanties, set out crops, and even established a post office in 1845. 28
   It isn’t clear whether any structure actually stood in this location that could be called a military installation then or later, or whether the troops were simply camped in the area near what had come to be known as the Fort Dade Community, but here they stayed, filling out their post returns for “Ft. Dade, Fla.” Gradually, even the old settlers who had called this place after the established military post on the river forgot, and succeeding generations never knew that there had been a “military” Fort Dade.
   This post office named for a forgotten fort shifted place throughout the area, a mile this way, two miles that, depending on the residence of each succeeding postmaster. Finally it settled in the rolling land some three miles west of the Fort King road. 29
But this Fort Dade too, was doomed. The railroad had come by this time and the rival community along the Fort King road that now called itself Dade City got the station and a post office of its own. Growing business in the area came to Dade City and its station and on April 15, 1889, the Fort Dade Post Office shut down for good. 30
By now memories of and references to Fort Dade had come to mean the peripatetic post office, and, with its demise, the tenuous tie of memory to the old fort faded and
was gone.
                       ----------------------------------------------

27 “Fort Dade is located in the vicinity of the Post Office bearing the same name and in 8 miles South of the Withlacoochee River and on the direct road to Tampa.” Post Return of Detachment 7th U. S. Infantry at Fort Dade for the Month of September, 1849.

28 Information on the Fort Dade Post Office has been taken from records
supplied by the Social and Economic Branch of the Office of Civil Archives of the National Archives and Records Service.

29 Details of the precise location of the Fort Dade Post Office were found
in a report to the topographer’s office of the post office department in December 1885 by then Postmaster Robert J. Marshall.

30. Office of Civil Archives, National Archives and Record Service.
 

The Fort King Road (click to see article)
The Florida historical quarterly  v.43 no.1 (1964:July) p.52-70

 Frank Laumer and William Goza retrace the path of Fort King Road which led from Tampa to the 1st Fort Dade.  They pass by the location of the military Fort Dade of  1849 located in Dade City.

Originally cleared as part of a military camp site, later a plantation and then a fort, this area has been a wooded, vacant tract for many years. The U.S. Army Seventh Infantry established the second Fort Dade here in 1849(or 1856).   (The first Fort Dade on the Withlacoochee River north of here had been closed after a few months in 1837.) It saw service during the Third Seminole War in 1856. The fort was then closed and thereafter the land was the Howell family farm from about 1867 to 1900, and was kept in its natural wooded state by the Nikolai family, who owned the property from about 1925 to 1970.

Note: This is now a wooded subdivision.

Notes from the Central Pasco Chamber of Commerce:
In 1849 the U.S. Army rebuilt Fort Dade near the present site of Community General Hospital in Dade City. The fort was used as a refuge for settlers during the Third Seminole Was after an Indian war party attacked the Bradley farm near what is now Darby community in central Pasco County. Two children were killed in the "Bradley Massacre", the last Indian attack on a settler's homestead east of the Mississippi.