cartography Cartography (; from grc, χάρτης , "papyrus, sheet of paper, map"; and , "write") is the study and practice of making and using maps. Combining science, aesthetics and technique, cartography builds on the premise that reality (or an im ...

, a phase line is a line to show most often changing phases of a military operation,

Military usage

The term is also used in

military terminology Military terminology refers to the terms and language of military organizations and personnel as belonging to a discrete category. As distinguishable by their usage in military doctrine, they serve to depoliticise, dehumanise, or otherwise a ...

to refer to an imaginary line on a map used to coordinate phases of operations. They are usually distinguished with different code names, varying by the particulars of the mission such as location and nature. By the same token, phase lines are frequently used after a battle or a

military campaign A military campaign is large-scale long-duration significant military strategy plan incorporating a series of interrelated military operations or battles forming a distinct part of a larger conflict often called a war. The term derives from the ...

historian A historian is a person who studies and writes about the past and is regarded as an authority on it. Historians are concerned with the continuous, methodical narrative and research of past events as relating to the human race; as well as the stu ...

s to describe what territory was controlled by which side at a given phase of the campaign.

Historical geography

Historical geographers use such techniques in a similar way, but written upon a longer time period. Dated phase lines on a map would indicate the growth or shrinkage of a

great power A great power is a sovereign state that is recognized as having the ability and expertise to exert its influence on a global scale. Great powers characteristically possess military and economic strength, as well as diplomatic and soft power inf ...

of the era such as the expansion of the

Roman Empire The Roman Empire ( la, Imperium Romanum ; grc-gre, Βασιλεία τῶν Ῥωμαίων, Basileía tôn Rhōmaíōn) was the post-Republican period of ancient Rome. As a polity, it included large territorial holdings around the Mediterr ...

, the spread of

Islam Islam (; ar, ۘالِإسلَام, , ) is an Abrahamic religions, Abrahamic Monotheism#Islam, monotheistic religion centred primarily around the Quran, a religious text considered by Muslims to be the direct word of God in Islam, God (or ...

Christianity Christianity is an Abrahamic monotheistic religion based on the life and teachings of Jesus of Nazareth. It is the world's largest and most widespread religion with roughly 2.38 billion followers representing one-third of the global pop ...

. Other familiar phase line mapping most experience in late elementary or middle school classes would be the extent of various ice ages or the

Ice Age An ice age is a long period of reduction in the temperature of Earth's surface and atmosphere, resulting in the presence or expansion of continental and polar ice sheets and alpine glaciers. Earth's climate alternates between ice ages and gree ...

consequential shrinkage or extension of continental landmasses down the continental shelves as the results of such climate changes.

References

{{Reflist Cartography Historical geography Military science Military cartography