Final answer:
Relief in Place is a military operation where one unit replaces another in a seamless transition to maintain continuous control. U.S. Army field manuals (FMs) provide the guidelines for such operations.
Step-by-step explanation:
The term "Relief in Place" in a military context refers to an operation in which one unit replaces another unit on the battlefield, ensuring a seamless transition of control. This operation is meticulously planned to maintain the continuity of defense or operation and to minimize vulnerability. For the U.S. Army, doctrinal guides including tactics and procedures for various operations such as relief in place are provided by Field Manuals (FMs).