Mercenaries are individuals or groups hired to fight in armed conflicts for financial gain rather than for political or national reasons. They often operate independently or as part of private military companies, providing military services such as combat, training, and security. Their involvement can raise ethical and legal questions, especially regarding accountability and the rules of war. Historically, mercenaries have played significant roles in various conflicts, from ancient times to modern warfare. Notable examples include the Swiss Guards in the Renaissance and the Blackwater company during the Iraq War. Their presence can influence the dynamics of a conflict, often complicating peace efforts.