Slingers were an element in the Roman army over many centuries. Their activities are frequently reported in literary accounts of battles and sieges during the civil wars of the Late Republic. Sling bullets, in stone, clay and lead, have been found at many scenes of conflict. Lead bullets often bear brief inscriptions addressed to the recipients, naming military units, their commanders and centurions; others carry sexual insults. This is an ever-expanding body of ancient evidence. Yet some books on the Roman army scarcely mention slingers. This monograph seeks to redress the balance and draws attention to their role and effectiveness. It covers the period between the Social War of 90-89 BC and the close of the civil wars at the battle of Actium in 31 BC, encompassing the campaigns of Julius Caesar in Gaul between 58 and 50 BC, including his expeditions to Britain, the wars between Caesar and Pompey the Great (and his sons) in 49-45 BC, and between Caesar's heirs and successors in 44-31 BC, including Mark Antony and the future emperor Augustus.