The Spanish War (Latin: Bellum Hispaniense or De Bello Hispaniensi) is a sequel to Caesar's commentaries, probably drafted by a junior officer. It recounts Caesar's campaign in Spain in 45 BC against the sons of Pompey and Labienus, his own former general in Gaul. Caesar's victory at Munda marked the final battle of the civil wars.
Free online Texts
Internet Classics Archive: The Spanish Wars, Translated by W. A. McDevitte and W. S. Bohn. HTML and TXT formats.
LacusCurtius: The Spanish War. Latin text with translation by A.G. Way. HTML format.
Latin Library: De Bello Hispaniensi. Latin text. HTML format.
Wikisource: Julius Caesar: The Spanish War. (attributed; possibly written by Aulus Hirtius or Gaius Oppius), translated by William Alexander McDevitte and W. S. Bohn. Online with PDF/MOBI/EPUB downloads available
The Great Conversation: Further reading at Tom's Learning Notes
Caesar: Commentaries on The Gallic War.
Caesar: Commentaries on the Civil War.
Caesar: The Alexandrian War.
Caesar: The African War.
Plutarch: Life of Caesar in the Parallel Lives.
Suetonius: Life of Caesar in Lives of the Twelve Caesars.
Latin Resources: Online materials for learning Latin.