The War with Catiline or Conspiracy of Catiline (De coniuratione Catilinae or Bellum Catilinae) by the Roman historian Sallust is an account of the turbulent political events of 63 BC, during which the senator Catiline plotted to seize the Roman government, only to be pre-empted by the consul Cicero. The rising Julius Caesar is portrayed sympathetically, protesting against Cicero's extra-judicial executions. This may be a reflection of Sallust's partisan sympathies at the time of writing, probably during the period of the civil wars two decades later.
Free online texts
Loebulus. L116 - Sallust -- War with Catiline. War with Jugurtha. Selections from The Histories. Doubtful Works. PDF of public domain Loeb edition in Latin and English.
The Latin Library: Bellum Catilinae. Latin text, HTML format.
Wikisource: The War with Catiline, translated by John C. Rolfe, 1931. HTML, downloadable as PDF/EPUB/MOBI.
Librivox: The Catiline Conspiracy and the Jugurthine War - public domain audiobook.
The Great Conversation: Further reading at Tom's Learning Notes
Sallust: The Jugurthine War.
Latin Resources: Online materials for learning Latin.