Located on the Rappahannock River near the head of navigation at the fall line, Fredericksburg developed as the frontier of colonial Virginia shifted west from the coast.. The Virginia General Assembly established a fort on the Rappahannock in 1676, just downriver of the present-day city.

As interest in the frontier grew, the colonial assembly formed Spotsylvania County in 1720, named after Royal Lieutenant Governor Alexander Spotswood. In 1728, Fredericksburg was declared a port for the county, of which it was then a part. Named for Frederick, Prince of Wales, son of King George II, the colonial town named its streets after the members of the royal family. In 1781, Fredericksburg was incorporated as a town 

The city has close associations with George Washington, whose family in 1738 moved to Ferry Farm in Stafford County near the Rappahannock River opposite Fredericksburg. Washington’s mother, Mary, later moved to the city, and his sister Betty lived at Kenmore, a plantation house then outside the city. Several citizens played active roles during the American Revolution (1763–1781). For example, a number of locals signed the Leedstown Resolves, which formed an association to protest the Stamp Act in the 1760s. In the 1770s, Fielding Lewis, owner of Kenmore Plantation and brother-in-law to George Washington, also operated an arms factory for the Continental Army. Thomas Jefferson wrote the Virginia Statute for Religious Freedom in Fredericksburg

During the 19th century, mills continued to be developed along the Rappahannock River, due to the abundance of easy power.The mills and easy power made the town a hub for grinding flour, processing and weaving cotton, and other manufacturing. Fredericksburg sought to maintain its sphere of trade, but with limited success. It promoted the development of a canal on the Rappahannock and construction of a turnpike and plank road to bind the interior country to the market town. By 1837, a north–south railroad, which became the Richmond, Fredericksburg and Potomac Railroad, linked the town to Richmond, the state capital. A much-needed railroad joining the town to the West’s arming region was not finished until after the Civil War.

During the Civil War, Fredericksburg was strategically important because of its port location midway between Washington and Richmond, the opposing capitals of the Union and the Confederacy. During the Battle of Fredericksburg from December 11–15, 1862, the town sustained significant bombardment and looting by the Union forces.

During that engagement, nearly 10,000 enslaved people left area plantations and city households to gain freedom by crossing the Rappahannock River to Stafford County and join the Union lines.John Washington, a literate enslaved person who shortly crossed to freedom, wrote later about people watching the approach of Union troops across the river from Fredericksburg: “No one could be seen on the street but the colored people. and every one of them seemed to be in the best of humors.”

The Second Battle of Fredericksburg was fought in and around the town on May 3, 1863, in connection with the Chancellorsville campaign (April 27, 1863 – May 6, 1863). The Washington Woolen Mill, a large three-story building, was converted to use as a hospital during the war.

After the war, Fredericksburg recovered its former position as a center of local trade and slowly grew beyond its prewar boundaries. Neither the city of Fredericksburg nor the surrounding counties however reached the 1860 level of population again until well into the 20th century. After the war, many freedmen moved to Richmond and Petersburg, where there had been established free black communities before the war, and there was more work.

In the early 20th century, as the Jim Crow era continued in the South, there was widespread population movement. Many African-Americans left rural areas of the South for work and other opportunities in industrial cities of the North and Midwest in a movement known as The  Great Migration. Some settled in Washington, D.C., where there were more opportunities, or further north.

War-related buildup at defense facilities for World War II caused population growth in the 40’s. The 1960s brought further  growth and development, fueled by the construction of Interstate 95, which eased commuting and trade. By the 1970s, the city and the area had become a bedroom community for jobs in Northern Virginia and Washington, D.C. Headquarters agencies, lobbyists, consultants, defense and government contractors, and a range of other businesses were part of the regional economy influenced by the U.S. government. The city also benefited from its relative proximity to four military installations: the United States Marine Corps’ Quantico Base, the U.S. Army’s Fort Belvoir, the U.S. Navy’s Dahlgren Surface Weapons Base, and the Virginia National Guard’s Fort A.P. Hill.

The University of Mary Washington was founded in Fredericksburg in 1908 as the State Normal and Industrial School for Women, to train white women for teaching K-12 and industrial skills. Adopting the name of Mary Washington College in 1938, the college was for many years associated with the University of Virginia (then limited to white men) as a women’s liberal arts college. The college officially desegregated in 1964. The college became independent of the University of Virginia and began to accept men in 1970. In 2004, the college changed its name from Mary Washington College to the University of Mary Washington. Two additional campuses for graduate and professional studies and education and research are located in Stafford County and in King George County, respectively.

Musician Link Wray of Fredericksburg developed the power chord of modern rock guitar in 1958 during his first improvisation of the instrumental piece “Rumble”, a single released by Wray & His Ray Men. This innovation became widely used by rock guitarists. In the early 21st century, the local music scene includes a wide variety of genres.

A commuter rail line – the Virginia Railway Express – was established in the 1980s, providing passage to Washington, D.C. and other cities north of Fredericksburg.

The city has become the regional healthcare center for the area. Retail, real estate, and other commercial growth exploded in the early 21st century, eventually slowing during the Great Recession beginning in 2007. Hispanic growth skyrocketed from 2011 to 2020, with Chancellor Green in nearby Spotsylvania County becoming a local enclave

There have always been Sin-Eaters in Fredericksburg or the Fredericksburg region for as long as humanity has lived and died in this area. Local Sin-Eater historians and ancient ghosts in the area report some of the first Sin-Eaters being a group of Indigenous people who are responsible for ensuring a number of the Avernian Gates in the area are still sealed. It was these Sin-Eaters who are said to have built the Obelisks deep within the Underworld. While many modern scholars are still researching the exact reason for these structures, the generally agreed upon reasoning is that in the ancient history of the region something woke up and the locals did what they had to in order to seal it closed. Rumors that the individual Sin-Eaters at the time had to sacrifice not only themselves but their geists to keep the Obelisks powered is a little worrying to say the least. 

The first European Sin-Eaters of note were recorded to have come to the area with the early Jamestown expeditions. The diary of a Sin-Eater named Joseph Hall chronicles his journey to the “New World” and his desire to establish a beachhead here under the mistaken belief that the ghosts and such were running rampant thanks to a lack of strong Sin-Eater presence. One can read his diary and journals and see the man’s original opinions and beliefs changing over time. The Journals never specify what happened to Hall but another journal by a Sin-Eater who was in Fredericksburg during its founding reports a strange man moving amongst the local forest with a tall gangly Geist following him. This Sin-Eater marks the first known Krewe in the area. Called the Scions of Aïdes. This Krewe established what would be the first of many traditions for the area, namely the Recording of Names. The Scions of Aïdes have since passed on but their influence is felt to this day. 

Modern Sin-Eater history really starts after the Civil War when the Council of Gates was established. The brutality of the fighting and around Fredericksburg was so great that multiple new Avernians Gates were created. In Fredericksburg itself Marye’s Heights and the graveyard that would come to be placed there would become one of the most active Avernian Gates in Virginia for some time. In fact after his death Richard Rowland Kirkland, the Angel of Marye’s heights would come back as a Sin-Eater and return to Fredericksburg where he worked alongside one the Krewes, The Masonic Order of the Pit, to help quiet the ghosts of Fredericksburg. The Masonic Order of the Pit, The Children of Faith, The Society of Mutes, and The Freedmen helped make up the original Council of Gates. Establishing most if not all of the city’s traditions moving forward.

For a time things were quiet and the Council could handle it. One by one though most of the Krewe’s moved on and for a time the Council of Gates was disbanded. That was until 2011. What would for most of the city’s residents be a small if a bit surprising earthquake, would mean a lot for the Sin-Eater community. A number of sealed Avernian gates were torn open and one of the Obelisks in the underworld cracked open and inside they found the long decayed body of one of the area’s ancient Sin-Eaters. His ghost was set free and now wanders the Underworld mumbling about the end of it all.

The council has been reformed. The Society of Mutes, and The Masonic Order of the Pit are the only two of the founding groups that came back in one way shape or form. The other Krewe’s that have been formed are The Department of Post-Mortem Services, The Ghost Riders MC, and Lorelei, Mallory, and Mortimer. The Council is working to curtail the opening of the various Avernian Gates that no one knew about and to figure out what exactly is going on with this earthquake and its aftermath.  The Council tends to monitor not only the city of Fredericksburg but they range pretty far into the various surrounding counties and cities.