Editing Isoroku Yamamoto (section)

==Battle of Midway, June 1942==
{{Main|Battle of Midway}}

Yamamoto's plan for Midway Island was an extension of his efforts to knock the American Pacific Fleet out of action long enough for Japan to fortify its defensive perimeter in the Pacific island chains. Yamamoto felt it necessary to seek an early, decisive offensive battle.

This plan was long believed to have been to draw American attention—and possibly carrier forces—north from Pearl Harbor by sending his Fifth Fleet (one carrier, one light carrier, four battleships, eight cruisers, 25 destroyers, and four transports) against the Aleutians, [[Battle of Dutch Harbor|raiding Dutch Harbor]] on [[Unalaska Island]] and invading the more distant islands of [[Kiska]] and [[Attu Island|Attu]].<ref name="Lightbody">{{cite book|last1=Lightbody|first1=Bradley|title=The Second World War|date=2003|publisher=Routledge|location=London|isbn=0-415-22404-7|page=136|edition= 1st|language=en|chapter=Part 5 – Containment}}</ref><ref name="Atlantic_Aleutians">{{cite news|last1=Kennedy|first1=David M.|title=Victory at Sea|url=https://www.theatlantic.com/magazine/archive/1999/03/victory-at-sea/306272/|access-date=29 January 2018|work=The Atlantic|issue=March 1999|publisher=The Atlantic|date=March 1999|language=en}}</ref>

While Fifth Fleet attacked the Aleutians, First Mobile Force (four carriers, two battleships, three cruisers, and 12 destroyers) would attack Midway and destroy its air force. Once this was neutralized, Second Fleet (one light carrier, two battleships, 10 cruisers, 21 destroyers, and 11 transports) would land 5,000 troops to seize the [[atoll]] from the [[United States Marine Corps|United States Marines]].

The seizure of Midway was expected to draw the American carriers west into a trap where the First Mobile Force would engage and destroy them. Afterwards, First Fleet (one light carrier, three battleships, one light cruiser and nine destroyers), in conjunction with elements of Second Fleet, would mop up remaining US surface forces and complete the destruction of the American Pacific Fleet.

To guard against failure, Yamamoto initiated two security measures. The first was an aerial reconnaissance mission ([[Operation K]]) over Pearl Harbor to ascertain if the American carriers were there. The second was a picket line of submarines to detect the movement of enemy carriers toward Midway in time for First Mobile Force, First Fleet, and Second Fleet to combine against it. In the event, the first measure was aborted and the second delayed until after the American carriers had already sortied.

The plan was a compromise and hastily prepared, apparently so it could be launched in time for the anniversary of the [[Battle of Tsushima]],<ref>Bicheno, Hugh. ''Midway''.</ref> but appeared well thought out, well organized, and finely timed, from a Japanese viewpoint. Against four fleet carriers, two light carriers, seven battleships, 14 cruisers and 42 destroyers likely to be in the area of the main battle, the United States could field only three carriers, eight cruisers, and 15 destroyers. The disparity appeared crushing. Only in numbers of carrier decks, available aircraft, and submarines was there near parity between the two sides. Despite various mishaps developed in the execution, it appeared that—barring something unforeseen—Yamamoto held all the cards.

Unknown to Yamamoto, the Americans had learned of Japanese plans thanks to the [[Magic (cryptography)|code breaking of Japanese naval code D]] (known to the US as [[JN-25]]).<ref name="Atlantic_Aleutians" /> As a result, Admiral [[Chester Nimitz]], the Pacific Fleet commander, was able to place his outnumbered forces in a position to conduct their own ambush. By Nimitz's calculation, his three available carrier decks, plus Midway, gave him rough parity with Nagumo's First Mobile Force.

Following a nuisance raid by Japanese [[flying boat]]s in May,<ref>Holmes, Wilfred J. "Jasper". ''Double-Edged Secrets'' and ''Undersea Victory''</ref> Nimitz dispatched a [[minesweeper (ship)|minesweeper]] to guard the intended refueling point for Operation K near [[French Frigate Shoals]], causing the reconnaissance mission to be aborted and leaving Yamamoto ignorant of whether the Pacific Fleet carriers were still at Pearl Harbor. It remains unclear why Yamamoto permitted the earlier attack, and why his submarines did not sortie sooner, as reconnaissance was essential to success at Midway. Nimitz also dispatched his carriers toward Midway early, and they passed the Japanese submarines ''en route'' to their picket line positions. Nimitz's carriers positioned themselves to ambush the [[1st Air Fleet|''Kidō Butai'']] (striking force) when it struck Midway. A token cruiser and destroyer force was sent toward the Aleutians, but otherwise Nimitz ignored them. On June 4, 1942, days before Yamamoto expected them to interfere in the Midway operation, American carrier-based aircraft destroyed the four carriers of the ''Kidō  Butai'', catching the Japanese carriers at especially vulnerable times.

With his air power destroyed and his forces not yet concentrated for a fleet battle, Yamamoto maneuvered his remaining forces, still strong on paper, to trap the American forces. He was unable to do so because his initial dispositions had placed his surface combatants too far from Midway,<ref name="Willmott, H.P. 1983">Willmott, H.P. ''Barrier and the Javelin''. Annapolis: United States Naval Institute Pres, 1983.</ref> and because Admiral [[Raymond Spruance]] prudently withdrew to the east to further defend Midway Island, believing (based on a mistaken [[USS Tambor (SS-198)#Second war patrol|submarine report]]) the Japanese still intended to invade.<ref name="blair">Blair, Clay, Jr. ''Silent Victory''. (Philadelphia: Lippincott, 1975).</ref> Not knowing several battleships, including the powerful {{ship|Japanese battleship|Yamato||2}}, were in the Japanese [[order of battle]], he did not comprehend the severe risk of a night surface battle, in which his carriers and cruisers would be at a disadvantage.<ref name="blair"/> However, his move to the east avoided that possibility. Correctly perceiving he had lost and could not bring surface forces into action, Yamamoto withdrew. The defeat marked the high tide of Japanese expansion.

Yamamoto's plan has been the subject of much criticism. Some historians state it violated the principle of concentration of force and was overly complex. Others point to similarly complex Allied operations, such as [[Operation MB8]], that were successful, and note the extent to which the American intelligence ''coup'' derailed the operation before it began. Had Yamamoto's dispositions not denied Nagumo adequate pre-attack reconnaissance assets, both the American cryptanalytic success and the unexpected appearance of the American carriers could have been irrelevant.<ref name="Willmott, H.P. 1983"/>