Spanish chronicles detail the process of military campaigns. First, the Aztecs looked for a legitimate reason to launch a new expedition (e.g., the murder of long-distance merchants, the absence of a tlatoani invited to attend an imperial ceremony, refusal to provide supplies or warriors to Aztec armies when they passed by). In such cases, they dispatched emissaries to ask the tlatoani if he were going to surrender without any resistance—a proposition that was always rejected. Then, Aztec leaders reassembled their military forces and sent them to the battlefield. Typical warrior equipment consisted of a padded cotton armor named ichcahuipilli, a wooden shield to prevent injuries and different kind of weapons; a macuahuitl (sword whose edges were composed of rows of razor-sharp obsidian blades); an atlatl (spear thrower), and bows and arrows. High-level warriors also wore sandals, jewels, specific headgear, and back devices.