This article describes the newest doctrine of the U.S. Armed Forces, i.e. the Multi- Domain Battle (MDB) concept. It constitutes a description of several operational principles related to a potential conflict with the People’s Republic of China or the Russian Federation, such as the time and space for conducting military operations, the operating environment, the forces (base of operations), the target, the concentration of forces and the operational leeway. The article looks at the origins of the doctrine, the circumstances under which it was formed and people who contributed to its development. The authors also refer to historical U.S. doctrines, such as the AirLand Battle or AirSea Battle concepts. Along with the authors’ enthusiastic approach to MDB, the article also features some critical opinions which imply that the U.S. Army is not ready for MDB operations. The research methods that were used by the authors included analysis, synthesis, comparison and generalisation. Much space is devoted to analysing the U.S. Army’s official documents, including Multi-Domain Battle: Evolution of Combined Arms for the 21st Century 2025-2040, FM 3-0 Operations and TRADOC Multi-Domain Battle: Combined Arms for the 21st Century. The authors believe that Multi-Domain Battle is about to become the official military doctrine of the U.S. Armed Forces. In spite of the criticism, transformations of individual combat teams in the MDB spirit should be expected in the upcoming years. This doctrine also provides a military response to the geo-political changes occurring in the world, manifested as the United State’s limited role in certain regions, China’s growing power and Russia’s aggressive foreign policy. The conclusions formulated in the article may serve as the starting point for further studies dealing, inter alia, with the Polish Army’s readiness for conducting military operations, based on the MDB doctrine, jointly with the U.S. Army, the Polish Anti-Access/Area Denial (A2AD) capabilities and the role of military technologies in the MDB doctrine. The article makes use of the exact translation of the term, i.e. “Multi-Domain Battle.” However, the reader should bear in mind that it describes capabilities not only at the tactical level but also in operational terms, enabling the accomplishment of the strategic objective.