A remarkable manuscript map apparently prepared for the invasion of Guadalcanal, compiling the geography of a prewar Hydrographic Office chart with more recent intelligence bearing directly on an amphibious assault. Its attention to beach conditions, coupled with the omission of the Japanese airfield at Lunga, strongly suggests that it was prepared before the Marines went ashore on August 7, 1942.

The map depicts most of the island, with particular attention to its coasts, and the densest treatment to the coast between Koli and Taivu Points (The main landings actually took place slightly to the west, between Koli and Lunga Points). Villages, mining camps, missions, plantations, trails, and rivers are shown, along with numerous mountain elevations, while great stretches of the mountainous interior remain almost blank. The compiler superimposed an alphanumeric grid on the sheet, allowing locations to be communicated even where recognizable landmarks were scarce.

At lower center the map states that it was “TRACED FROM OVERLAY PREPARED BY G-2 ROSES / MAP # G2-R.” In layperson’s terms, this tells us the map is a tracing of one produced by an intelligence unit on the island of Efate (code name “Roses”) in the New Hebrides,[1] roughly 800 miles southeast of Guadalcanal, where an advance air and naval base was being developed during the spring and summer of 1942.²

Playing cartographic catchup
The American amphibious force went in with inadequate maps. An official Army history states flatly that “There were no good maps of Guadalcanal, a deficiency that was, in fact, never remedied throughout the campaign.” The same source indicates that the 1st Marine Division intelligence section relied in part on U.S. Hydrographic Office chart no. 2916, Guadalcanal and Florida Islands, which it enlarged but considered inaccurate and out of date (Click here for a somewhat later map printed by the Marines based on chart no. 2916.) This was augmented by “a crude sketch which had been prepared by colonial officials before the war [that] aided in locating some trails and buildings but lacked contour lines and elevations,” as well as by reconnaissance photographs of the north coast taken in June 1942.[2]

Of particular relevance here, a nine-sheet strip map for the landing was compiled from aerial photographs taken in late June. It covered the north coast from Lunga Point east to Aola—thus including the entire Koli-Tetere-Taivu sector—and had been reproduced before the amphibious force left Wellington. On July 17 Marine reconnaissance also observed cleared areas at both Lunga and Tetere.[3]

The manuscript map offered here is clearly a result of this improvisational process. Its underlying geography is derived, directly or indirectly, from Hydrographic Office chart no. 2916, with notable additions particularly on the north shore between Koli and Taivu Points.

Prepared in advance of the invasion
The first evidence for a pre-invasion date is the concentration of amphibious intelligence between Koli and Taivu. The legend defines “B” as “beach width in feet,” and the coast from Koli to Taivu bears dozens of these measurements. Though Beach Red lay farther west, the emphasis here is entirely consistent with pre-invasion planning: the Marines already possessed aerial mapping of the sector, and by July 30 intelligence placed a small Japanese garrison and possible second airfield at Tetere.[4]

Even more striking is what the map leaves out: the Japanese airfield at Lunga, Henderson Field, the American perimeter, and other features introduced immediately after August 7. By August 2 the Marines had received photographs showing the Lunga airstrip nearly complete, making its absence here strong evidence for an earlier compilation.[5]

The orange colored-pencil markings between Koli and Taivu beaches may be notations made after the landing, but their significance is unclear.

In all, a remarkable survival from the hurried intelligence effort preceding the Guadalcanal invasion, recording both what American planners knew about the island and how much they did not.

[1] Per the code word glossary of the U.S. Naval History and Heritage Command.

[2] John Miller, Jr., Guadalcanal: The First Offensive (Washington: Center of Military History, U.S. Army, 1995), p. 45.

[3] Ibid.

[4] The Landing in the Solomons, 7–8 August 1942 (Office of Naval Intelligence, 1943; Naval History and Heritage Command reprint, 2017), pp. 3–4

[5] Miller, op. cit.