Unit 5: Period 5 (1844–1877)
AP US History: 58 practice questions with detailed explanations.
Unit Study Guide
Executive Summary
Period 5 is the crisis of the Union: manifest destiny, the Mexican War, sectional collapse, civil war, and Reconstruction.
Expansion and sectional crisis
Manifest Destiny drove annexation of Texas (1845) and the Mexican-American War (1846–48), which added the Southwest. The Wilmot Proviso's attempt to ban slavery there failed, but the question would not go away. The Compromise of 1850 (stronger Fugitive Slave Act) and the Kansas-Nebraska Act (1854, popular sovereignty) inflamed both sides; Bleeding Kansas and the Dred Scott decision (1857) deepened the divide.
The road to war
The Republican Party formed opposing slavery's expansion. John Brown's raid (1859) terrified the South. Lincoln's 1860 election triggered secession; Fort Sumter (April 1861) began the war.
The Civil War (1861–65)
The Union's advantages — population, industry, railroads — met Confederate generalship. The Emancipation Proclamation (1863) reframed the war around freedom; Gettysburg and Vicksburg (1863) turned the tide; Sherman's march broke the South's will. Lee surrendered at Appomattox (April 1865).
Reconstruction (1865–77)
Lincoln's 10% plan, Johnson's leniency, and Congressional (Radical) Reconstruction competed. The 13th, 14th, and 15th Amendments abolished slavery, granted citizenship/equal protection, and protected Black male voting. Freedmen's Bureau schools and Black officeholding marked progress; Black Codes, the KKK, and sharecropping fought back. The Compromise of 1877 withdrew federal troops, ending Reconstruction.
Exam traps
The Emancipation Proclamation freed only Confederate-area enslaved people — not the border states. Reconstruction's failure was political retreat, not Black incapacity. The 14th Amendment's equal protection became the future civil-rights lever. The war began over secession, though slavery was its root cause.