WW2 · TURNING POINT · 1940

Chain Home radar (1940)

On the WW2 map as “Radar & the Channel”

1940 — Chain Home radar detects raids approaching across the Channel. It sometimes gives Fighter Command around 20 minutes to direct fighters toward them.

When: 1940
Type: Turning point
Chapter: Battle of Britain (chapter 4 of WW2)
Atlas: The War Room — WW2, 1936–1945

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Map showing Chain Home radar (1940), turning point in The War Room — WW2, 1936–1945 — TURNING POINT · THE WAR ROOM — WW2, 1936–1945

These maps are reconstructed from published sources · Cliopatria v0.2.1 — dated political boundaries · French Ministry of the Armed Forces — La ligne de démarcation · IGM Fiume, 1:25,000, sheet53B II SE — boundary established in1924 · Natural Earth — physical reference geography · Yugoslavia (1929–1939) location map — international frontier and Adriatic coast · Treaty of Rome (1924), division of Fiume and west-bank boundary · Murli / rowanwindwhistler — Slovakia border changes, 1938–1945 · United States Holocaust Memorial Museum — The Holocaust in Slovakia · Slovak Nation’s Memory Institute — The First Vienna Award

Source details

Cliopatria contributors / Seshat Global History Databank. CC BY4.0 · Dated polity and constituent territory selections; campaign-dependent occupation overlays reconstructed separately.
Ministère des Armées. Historical facts consulted; actual polygon imported from Cliopatria
Istituto Geografico Militare, Fiume (printed1946; 1927 survey with1931–1940 updates), reproduced by Istituto regionale per la storia della Resistenza e dell’Età contemporanea nel Friuli Venezia Giulia. Independent reconstruction from graticule coordinates and boundary observations; archive page reserves artwork rights.. Geographical-fact reconstruction; original archive artwork not distributed
Natural Earth. Public domain
NordNordWest/Wikipedia. Converted from the published SVG to WGS84; eastern Italian regional territory extracted. Source cites Velhagen & Klasings Großer Volksatlas (1938).. CC BY-SA 3.0 Germany
1924 agreement interpreted alongside the regional history institute and City of Rijeka’s explanation of the Donja/Gornja Drenova division.. Historical geographic facts; citation only
Murli; SVG adaptation by rowanwindwhistler (2021). CC BY-SA 2.5; derived geographic paths under the same license · Georeferenced actual published vector regions using eight printed city positions; no map artwork or labels in the atlas.
United States Holocaust Memorial Museum — The Holocaust in Slovakia. Historical chronology consulted; no source prose or artwork republished
Slovak Nation’s Memory Institute — The First Vienna Award. Historical territorial chronology consulted; no source artwork or prose republished

Slovak territory is reconstructed from the published 1938–1945 border-change map, which separates the client state from Hungarian and German annexations. This regional source does not resolve small northern frontier changes or survey-level detail. After August 1944, German military occupation supersedes the client-state fill.

The eastern Italian frontier uses the published 1930s regional map and a reconstruction of the 1924 Fiume boundary. Source conquests after April 1941 remain separately dated.

The dates of published political outlines retain the resolution available in their sources. Military fronts and operational perimeters have their own source and method records.

reconstruction: 1936–1940 · reconstruction: 1936–1941 · reconstruction: 1936–1942 · reconstruction: 1939–1944 · reconstruction: 1940.5 · reconstruction: 1940–1940 · reconstruction: 1940–1941 · vector: 1912–1955 · vector: 1924–1940 · vector: 1936–1941 · vector: 1936–1944 · vector: 1936–1945 · vector: 1938–1972 · vector: 1939–1944 · vector: 1939–2023 · vector: 1940–1940 · vector: 1940–1941 · vector: 1940–1942 · vector: 1940–1943

Layer records and reconstruction methods

In the same chapter

✕ The Blitz

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Chain Home radar (1940)

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