Teamwork represents an essential element within any group, including military units. Establishing a unit based on teamwork, characterized by a high level of cohesion, is crucial for achieving objectives and ensuring the success of a military unit. All team members participate in fostering team spirit and building strong cohesion, but the role of the commander in this process is of utmost importance. The commander is a person who encourages mutual cooperation, maintains a positive atmosphere, builds the team spirit of the unit and directs the members of the team towards a common goal. The paper discusses different groups and their characteristics, as well it outlines the procedures for establishing a military unit as group. Furthermore, it highlights the importance of cohesion and effective leadership within a military unit, which are essential for successful military task completion. The emphasis throughout the paper is on cohesion and collaboration, and it demonstrates the significance of teamwork using examples from the Croatian Navy.