An invasion of the continental United States would have required detailed planning and meticulous preparation prior to the invasion force being delivered to the battlefield. The first step would have involved isolating the Pacific Coast battlefield from the rest of the United States.
The fact that the Coast was connected to the rest of the country by a finite number of narrow and fragile corridors was a golden opportunity. As described in detail in Chapter Five, the rail and highways in these narrow corridors passed through remote, rugged and lightly populated areas. Here, there were numerous tunnels, highway bridges, and railroad trestles that were in isolated locations. In most cases, they were hundreds of miles from an alternate route. Likewise, telephone and telegraph lines, which generally paralleled highways and railroads, were extremely vulnerable and would be difficult to repair without road access. The prior insertion of a small number of covert sabotage teams in the weeks ahead of the actual invasion would have had the goal of cutting most, if not all of these lines of communication.
Turning to the invasion itself, Japanese planners would have considered timing and settled on the scenario of “as soon as possible after Pearl Harbor.” Next, they would have considered the forces available and the invasion locations.
In Chapter Twenty-Four, I noted that five field armies out of a total of about two dozen in the Imperial Japanese Army were earmarked for the December 1941 Southeast Asia and Hong Kong campaigns. If these operations were cancelled or greatly truncated, those five armies could have been reassigned to an invasion of the Pacific Coast.
For the sake of this hypothetical exercise, let’s assume that the forces used in the Pacific Coast Theater were those that, in 1941, had been assigned to the Southeast Asia Theater. Instead of a Southern Expeditionary Army Group, General Count Hisaichi Terauchi would have commanded an America Expeditionary Army Group. Instead of headquarters in Saigon, Terauchi would have first exercised command at sea. Once ashore, he certainly would have been tempted to establish his headquarters in what was then the greatest city on the West Coast—San Francisco—and probably in the former offices of General John DeWitt at the Presidio of San Francisco.
Insofar as strategic objectives were concerned, Japanese planners probably would have drawn on the Japanese experience in China to guide them. There, where it must be noted the Japanese had successfully taken a country with an area nearly twenty times greater and a population nearly five times greater than Japan’s, the first objectives had been the major coastal cities of China, such as Shanghai and Canton, and then a concerted move to seize almost all of China’s coastline.
The objectives of the Japanese, therefore, would have been Seattle and the naval base at Bremerton across Puget Sound, then Portland with, perhaps, a tertiary mission of securing at least some of the Columbia River dams. In California, San Francisco and Los Angeles would have been essential strategic goals as would have been San Diego, with its great naval facility.
Another essential strategic goal, of course, would have been the destruction of the four U.S. Army divisions stationed along the West Coast, especially those commanded by General Joe Stilwell and concentrated between Monterey and San Luis Obispo.
Japanese naval assets would have been divided into three task forces, each centered on a carrier division of the 1st Air Fleet, which included Akagi and Kaga in the 1st Division, Soryu and Hiryu in the 2nd Division, and Shokaku and Zuikaku in the 5th Division. A task force would have been allotted to support the landings in the Pacific Northwest, and the other two would have divided between the landings in Northern California and Southern California. To its usual escort, each division would have been supported by additional destroyers, as well as several cruisers and perhaps two battleships each.
To face this formidable array of naval power, the U.S. Navy had only fourteen destroyers, half of them in San Diego and four in San Francisco Bay. The only battleship, the USS Colorado, was being overhauled at Bremerton, and the only cruiser, the USS Concord, was being overhauled in San Diego. The Pacific Fleet’s three aircraft carriers would have been at sea. The USS Enterprise and USS Lexington were west of Hawaii, having luckily missed the Pearl Harbor attack, while the USS Saratoga, which had been in San Diego on December 7, departed for Pearl Harbor the following day.
The IJN, therefore, could have matched the U.S. Navy’s entire available Pacific Coast force with any of its three task forces whether or not the USS Saratoga returned to respond to a Japanese attack on the West Coast. Prior to the commencement of hostilities, the locations of American ships were well-known. Yamamoto, therefore, would have had an additional advantage when he planned naval operations on the Pacific Coast.
In all likelihood, the IJN’s actions would have commenced with a carrier strike against naval facilities and any ships in port. If any of the destroyers had emerged to fight, Japanese surface forces would have given them battle, and it probably would have turned out to be like those fought in Southeast Asia in late 1941 and early 1942 especially as with the Battle of the Java Sea at the end of February 1942. It would have been a lop-sided Japanese victory.
If the Saratoga had returned to defend the Pacific Coast, chances are that she would have been overwhelmed by Japanese aircraft and suffered the same fate as HMS Hermes off Ceylon in April 1942.
When we think of amphibious landings in World War II, we probably think of operations like Tarawa and Iwo Jima in the Pacific or Salerno and Normandy in Europe, in which soldiers or Marines assaulted well-fortified, heavily defended positions, often under intense artillery and machine gun fire. In mid-December 1941, virtually the entire Pacific Coast was undefended. There were no troops stationed at probable invasion beaches. The only fortifications were the Coast Artillery forts that guarded the entrances to California ports, the mouth of the Columbia River, the entrance to Puget Sound, and these could be bypassed by invading troops.
In terms of airpower, the Japanese had a roughly two-to-one advantage over the Americans in number of aircraft, and, more precisely, in the number of fighter aircraft available for air-to-air combat. Qualitatively, the Japanese Mitsubishi A6M Zero was superior to most of the American types, and the Japanese fighter pilots had extensive training and substantial combat experience—including their recent actions over Pearl Harbor.
As at Pearl Harbor, the first strike by Japanese carrier aircraft would have been aimed at American airfields, especially those at which fighters were based. In the north, USAAF interceptor bases at Portland Airport and Paine Field, north of Seattle along with U.S. Navy airfields in the Puget Sound area, would have topped the target list. In California, Hamilton Field, north of San Francisco, and March Field in Riverside County would be the first to be attacked. Putting these bases out of action would have essentially given the Japanese control of the skies.
With their fighter protection eliminated, the bomber bases at Spokane, Washington and Pendleton, Oregon, as well as in California’s Central Valley, would have been vulnerable to attack from the air as well. They also would have been forced to make any attacks against the invaders without the benefit of fighter escort.
The Japanese would have depended on carrier air power at the beginning. But to conduct sustained air operations against targets inland, the Japanese would have needed longer range bombers such as were used to support operations in Southeast Asia. Just as the IJN Air Force possessed Japan’s most formidable fighter plane in the Zero, it also operated the most effective Japanese medium bomber of World War II, the twin-engined Mitsubishi G4M (later known to the Allies as the “Betty”). This aircraft, however, did not have the range to reach the Pacific Coast from Japanese bases, nor could it operate from a carrier.
This conundrum could have been resolved by delivering crated bombers to the Pacific Coast by ship and assembling them at bases established ashore. The Betty was a rugged plane that did not need huge concrete runways in order to operate. Small coastal airports or simple grass strips would have sufficed. Other options to bolster Japanese air-power would have been to use the smaller, slower carriers to act as ferries for aircraft of the Imperial Japanese Army Force. Also, flying boats, such as the Kawanishi H8K, which was used for the second raid on Pearl Harbor, and floatplanes, such as the Aichi E13A, both supported by seaplane tenders or ad hoc shore bases, could have provided a stop-gap while land-based air power was established.
It is tantalizing to think that the Japanese might have fulfilled one of the more popular conspiracy theories of December 1941 by capturing airfields in Baja California and using them to mount attacks on southern California.
When considering the locations for the three main landings, Japanese planners would have been looking for lightly defended areas, relatively close to the major cities and set in relatively flat and open terrain in order to allow troops to move swiftly off the beach and toward their objectives. Although the Pacific Coast may have been connected tenuously to the rest of the United States by few highways, the road network on the Pacific Coast, especially within one hundred miles or so of the coastline, was excellent. Just as the modern highway built in Malaya by the British greatly aided the Japanese drive to Singapore, American roads would have given an advantage to the invaders as much as they did to the defenders. Access to this road network, therefore, also would have been an attractive feature that Japanese planners would have been pleased to exploit.
In 1909, shortly after the Russo-Japanese War changed the role and standing of the Japanese Empire on the world stage, a man named Homer Lea wrote an insightful book entitled The Valor of Ignorance. A Stanford-educated self-styled adventurer, Lea was a co-founder of Roswell, New Mexico and spent several years in China at the turn of the twentieth century, where he served as a confidant of future Chinese leader Sun Yat-sen and as a lieutenant general in the Baohuanghui army. In his book, he laid out a detailed criticism of the unpreparedness of the United States military establishment, and presented a scenario for a Japanese invasion of the Philippines and the United States. His description of the Philippines campaign, including the amphibious landing sites, is exactly as it actually occurred thirty-two years after he wrote about it.
In the Pacific Northwest, Lea suggested Willapa Bay and Grays Harbor, twenty-five miles apart on the Washington coast, as landing sites. Both are deep inlets that would shelter an invading force from often rough seas and inhospitable mid-winter weather of the North Pacific. They also are less than 200 miles from Seattle and Portland.
Once the invading force was ashore, it probably would have moved to capture Aberdeen, which is on Grays Harbor and which had an airport. The invaders could have reached Olympia on the second day, capturing a state capital and, more important, putting the Japanese astride U.S. Route 99, then the only major highway between Seattle and Portland.
Meanwhile, to attack Portland from the south without having to cross the Columbia River, a Japanese force might have landed at Newport, Oregon, the western terminus of U.S. Route 20. They would have gained access to good roads as well as a small facility adequate for unloading troops and a small airfield. They would have been only around 130 miles from Portland and could have attacked from the south through the level, open terrain of the Willamette Valley.
In central California, with an eye toward taking San Francisco, perhaps the best place to land amphibious troops was by way of the relatively calm waters and open beaches of Monterey Bay, about 120 level miles south of the Golden Gate. There are good beaches farther north, but landing at those locations would require crossing the steep and rugged coastal mountains.
Lea suggested that U.S. Army troop concentrations should be in the Santa Clara Valley, forty-five miles south of San Francisco, and seventy-five miles north of Monterey Bay. In fact, in 1917 during World War I and five years after Lea’s death, the U.S. Army did him one better, establishing the gunnery range on Monterey Bay that evolved into Fort Ord, the home of the 7th Infantry Division, one of only two Regular Army divisions in the Western Defense Command.
Terauchi would have wanted to engage and defeat the 7th Infantry Division eventually, but his first task would have been to get at least one of his divisions safely ashore. Therefore, a feint either north or south to draw off some of the defending force might have been necessary before conducting the actual landing.
Terauchi might have decided to make an exceptionally bold move: to attack San Francisco directly. The unimaginatively named Ocean Beach, a straight, four-mile stretch of sandy shoreline defines the western edge of the city. Rocky Point Lobos at the north end juts into the Pacific and would prevent the coastal artillery arrayed around the Golden Gate from targeting invaders coming across Ocean Beach.
Once ashore, an invader would have a choice of nearly two dozen perfectly straight streets leading directly toward the heart of the city. City Hall is but five level miles away, with the city’s financial district, then still considered the “Wall Street of the West,” less than two miles beyond. General DeWitt’s office at the Presidio was only five miles from Ocean Beach.
Immediately south of Monterey, the steep terrain of the Big Sur coast presents its own difficulties. Farther south, however, near San Simeon and Cambria, nearly one hundred miles south of Monterey, there are good beaches suited to amphibious operations, with a relatively level passage on California Route 1 to the U.S. Route 101 corridor at San Luis Obispo. Indeed, this area had been used by the U.S. Army for prewar amphibious exercises.
However, these beaches are only about thirty miles north of the California National Guard base at Camp San Luis Obispo, which was then home to the 40th Infantry Division. Meanwhile, the beaches near Santa Maria, about fifty miles south of Camp San Luis Obispo present an opportunity for a second landing, but again with the drawback of being close to the base of a defending division. Alternatively, either site might be used either for an actual landing and the other for a deception operation.
Once ashore successfully in this area, a Japanese force could occupy the central coast and be positioned roughly 200 highway miles from both San Francisco and Los Angeles so as to be available to move either direction to support other landings.
As San Francisco was the objective in Northern California, Los Angeles and San Diego were those in Southern California. One option would have been a landing between the two, perhaps north of Oceanside in the lightly populated area that would eventually become the U.S. Marine Corps’ Camp Pendleton. This would put the invading force ashore seventy-five miles south of downtown Los Angeles, sixty-five miles from the Ports of Los Angeles and Long Beach, and fifty miles north of San Diego, all via the broad and well-maintained U.S. Route 101. The same naval force that conducted any action against Naval Base San Diego could have easily supported operations here without even moving the aircraft carriers.
North of Los Angeles, a landing in rural Ventura County near the city of Oxnard, would have placed the invader about sixty miles west of downtown, again via Route 101. About forty miles to the northwest of Oxnard, Terauchi could have made a regimental-sized landing aimed at capturing the petroleum refining complex around Santa Barbara that was later to be the target of Kozo Nishio’s I-17.
As in a direct assault across Ocean Beach in San Francisco, Terauchi might also have considered the same for Los Angeles. Landing his troops on the picturesque sandy beaches of Santa Monica Bay south of Malibu, would put them less than twenty miles from downtown Los Angeles or Hollywood, and less than ten miles from the Inglewood oil fields or Beverly Hills. They would also be outside the radius of fire from the big guns of Fort MacArthur, which were situated to protect the entrances to the harbors of Los Angeles and Long Beach.
As in San Francisco, the invaders might have made rapid progress on city streets, such as Santa Monica Boulevard, and raced deep into the county, perhaps as far as Pasadena, via the Arroyo Seco Parkway on the first day or two of the invasion. Then again, the volume of traffic present on Los Angeles streets—infuriatingly heavy then, as now—might well have impossibly snarled both the advance of the Japanese, as well as the evacuation of frightened refugees, for many days.
As was the case with the operations of the five field armies of his actual Southern Expeditionary Army Group, Hisaichi Terauchi’s hypothetical America Expeditionary Army Group would have been prepared to move quickly, a blitzkrieg–style operation aimed at covering great distances, capturing key points, and keeping the Americans off-guard. Also, as in Southeast Asia, there would be an emphasis on simultaneous action across the entire Pacific Coast Theater. Whether it was on December 12 or December 14, Invasion Day would have been Invasion Day at locations from San Diego to Willapa Bay.