Baptism of fire, also known as baptism by fire, signifies a severe introductory or initial experience. In a military context, it specifically denotes a soldier's first encounter with enemy fire. The phrase can describe any difficult first experience, as illustrated by a novice skier tackling a challenging slope. This military sense dates back to at least a 1907 Civil War history. Both the military and general metaphorical uses of the phrase allude to a Biblical passage from Matthew 3:11. This passage describes a baptism with the Holy Spirit and fire. The term's use for a spiritual baptism originates from the early 1600s. Its non-biblical, metaphorical application for any difficult initiation emerged in the mid-1850s. Therefore, the phrase encompasses both literal combat and figurative severe first ordeals. It highlights the intensity of an initial, challenging encounter.