The Southern Victory series or Timeline-191 is a series of eleven alternate history novels by author Harry Turtledove, beginning with How Few Remain (1997) and published over a decade. In the series, the Confederate States defeats the United States of America in the American Civil War, making good its attempt at secession and becoming an independent nation. Subsequent books build on this alternate timeline through the mid-1940s.

The secondary name is derived from General Robert E. Lee's Special Order 191, which detailed the C.S. Army of Northern Virginia's invasion of the Union through the border state of Maryland in September 1862. Union soldiers found a copy of the order on September 13, which helped General George B. McClellan of the Army of the Potomac prevail over Lee at the Battle of Antietam. Turtledove creates a divergence by positing that the Union does not find the order.

The Southern Victory series consists of 11 books, published between 1997 and 2007. The first book in the series is How Few Remain, and the remaining 10 form three sub-series: The Great War (1998–2000) trilogy, The American Empire trilogy (2001–2003), and The Settling Accounts (2003–2007) tetralogy. (The author changed some aspects of the timeline and narrative between How Few Remain and the remainder of the series, producing some inconsistencies.)

After recovering the lost copy of Special Order 191 before it falls into Union hands, Confederate forces catch George B. McClellan's Union Army by surprise and destroy it on the banks of the Susquehanna River in 1862. Occupying Philadelphia, the Confederacy gain diplomatic recognition from the United Kingdom and France, who mediate a peace deal by which the Confederacy achieves independence. President Abraham Lincoln considers his failure to issue the Emancipation Proclamation, along with the possibility of the U.S. finding its own European allies in the future.

The United States cannot afford Alaska, but proceeds with its war against the natives of the Great Plains. Meanwhile, the Confederacy admits Kentucky, Sequoyah, and Cuba as new states, and negotiates the purchase of Sonora and Chihuahua from Mexico in 1881. Republican President James G. Blaine uses this as a casus belli to declare a renewed war, drawing Britain and France back into the conflict. The Union, despite its advantage in manpower and resources, lacks competent leadership, and struggles to take Confederate territory while also facing a revolt in Utah. The Louisville campaign devolves into trench warfare, while Britain and France shell U.S. ports and New Brunswick annexes northern Maine. The Union capitulates in early 1882, recognizing the Confederate acquisitions, while the Republicans are soon voted out of government.

In the wake of the war's loss, Lincoln leads his loyal faction of the Republican Party into merging with the nascent Socialist Party of America, changing US politics as this becomes the second major party, supplanting the Republicans afterward. Over the rest of the decade, manumission of slaves is nominally implemented throughout the Confederacy—easing relations with Britain and France, which had both abolished slavery much earlier—although the black population continues to live in apartheid-like conditions. The U.S. secures an alliance with the new German Empire amid a national atmosphere of revanchism.

Upon the assassination of Archduke Franz Ferdinand, Britain, France, and Russia go to war with Germany and Austria-Hungary. Presidents Theodore Roosevelt and Woodrow Wilson order the U.S. and C.S. militaries to mobilize following their respective allies, and fighting soon breaks out. Industrialized warfare and the absence of European intervention favors the Union side, and much of the Confederate officer corps is made up of heirs of great 19th-century generals with no particular talent of their own. An invasion of Maryland and Pennsylvania overruns Washington, D.C., but is unable to take Baltimore, while the Union launches attacks on Sonora and Canada, along with the capture of the British Sandwich Islands. As winter falls, a stalemate settles in across trench lines in Kentucky, Pennsylvania, Virginia, Manitoba, Southern Ontario, and the St. Lawrence River. The U.S. faces another rebellion in Utah and the C.S. faces a black socialist revolt, which takes a year to subdue.

In 1916 a new technical advance is introduced: the "barrel". George Armstrong Custer develops a doctrine for armored cavalry, but his tactics are not adopted and the first offensive is a failure. The U.S. successfully advances in Canada and defends Hawaii in a large naval engagement; the C.S. hopes that attrition and war weariness might knock the U.S. out, but pro-war President Roosevelt wins reelection, and the Confederacy is forced to begin recruiting black troops with a promise of civil rights after the war. The following year sees breakthroughs in Tennessee and Quebec using Custer's massed barrel tactics, while a simultaneous advance in Virginia recaptures a devastated Washington. With Union troops approaching its capital, the C.S. sues for peace, with it suffering the same fate as Germany in our timeline. Territorial changes include Kentucky and the western half of Texas (henceforth known as Houston) being annexed into the U.S. as states. The C.S. States of Arkansas, Sonora, and Virginia lose territory to the U.S. states of Missouri, New Mexico, and West Virginia respectively, and Sequoyah is placed under occupation by U.S. forces. All of Canada (except Quebec, which is released as a U.S. ally) is annexed by the U.S. under occupation. In Europe, army mutinies lead to France's exit from the war; Italy never enters it, while Russia is wracked by revolution. Brazil also joins the Central Powers along with Chile and Paraguay against Argentina, and increasingly isolated, Britain capitulates as well, ending the war.