Before the War

Japanese Immigration to Hawai’i

In 1940, Hawaiʻi was still a territory of the United States — statehood would not be achieved until 1959. Thriving fields of sugar cane dotted the landscape of most of the Hawaiian Islands. They had been made productive and profitable with immigrant labor, first from China and then from Portugal.

The first large-scale group of immigrants from Japan arrived in Hawaiʻi in 1885, following an agreement between the Kingdom of Hawaiʻi and the Japanese government to supply laborers for the growing sugar plantation industry. At the time, the Japanese government strictly regulated overseas travel, and emigration was permitted only under official sanction.

These early migrants, known as kanyaku imin (government-sponsored contract immigrants), were recruited to work primarily on sugar plantations. Tens of thousands more followed in subsequent decades, many coming from economically disadvantaged rural areas — especially the prefectures of Hiroshima, Yamaguchi, and Kumamoto, as well as Okinawa.

In 1898, the United States annexed Hawaiʻi, and in 1900 it became a U.S. territory. Despite this political change, Japanese immigration to the islands continued into the early 20th century.

Settlement and Family Formation

Although many immigrants initially intended to return to Japan, harsh plantation conditions often limited their ability to save money, and the high cost of return travel made leaving difficult. Over time, many chose to remain in Hawaiʻi and pursue opportunities beyond plantation labor. Instead of returning home, many men chose to establish families in Hawaiʻi by arranging marriages with women in Japan through the “picture bride” system. These women traveled to Hawaiʻi to join husbands they had never met in person, helping to stabilize and grow the community.

The first-generation Japanese immigrants, the Issei, gave birth to the Nisei, the second generation, who were American-born citizens of Japanese ancestry. The majority of the soldiers of the 100th Infantry Battalion were drawn from this Nisei generation, although some were even Sansei (third generation), reflecting the deep roots of Japanese families in Hawaiʻi.

These Americans of Japanese ancestry (AJA) were raised in a multicultural environment where traditional Japanese values such as loyalty and duty to family, community, and country were blended with the American principles of freedom and democracy that they learned in public schools. Although raised in close-knit Japanese communities, they were also influenced by Native Hawaiian culture as well as the diverse customs and traditions of the many immigrant groups that had settled in Hawaiʻi.

Citizenship

Until 1924, Japanese nationality law granted citizenship through the father, meaning that many children born to Japanese fathers automatically received Japanese citizenship regardless of birthplace. In contrast, the United States granted citizenship to anyone born on U.S. soil under the 14th Amendment to the Constitution. As a result, many Japanese Americans born in Hawaiʻi before 1924 held dual citizenship in both Japan and the United States.

In 1924, the U.S. Congress passed the Immigration Act of 1924 (National Origins Act), which effectively ended immigration from Japan. That same year, Japan revised its nationality laws so that children born outside Japan would no longer automatically receive Japanese citizenship unless their birth was registered with a Japanese consulate within a limited period. The revised law also made it easier for American-born children of Japanese immigrants to renounce their Japanese citizenship. Previously, men subject to military conscription could not easily renounce their Japanese citizenship and remained liable for compulsory military service if they resided in Japan. After 1924, Nisei could renounce Japanese citizenship even during draft age, removing potential obligations to serve in the Japanese military. However, many AJAs were unaware that they held dual citizenship or did not fully understand the legal process required to renounce their Japanese nationality, and therefore remained dual citizens without realizing it.

Growth of the Japanese American Community

By 1924, approximately 110,000 people of Japanese ancestry lived in Hawaiʻi. By 1940, that number had grown to about 158,000, with roughly two-thirds of them American-born citizens.

While many Issei remained on plantations to raise their families, where conditions had gradually improved through organized labor efforts, others yearned for a life beyond the sugar cane fields, opening small businesses or working as skilled tradesmen. Like other ethnic groups who immigrated to the United States, the Issei placed a strong emphasis on education, sacrificing greatly to provide better opportunities for their children.

Despite these efforts, racial discrimination limited employment opportunities for AJAs, even those with college degrees, and barred most from positions in large Caucasian-owned companies. As a result, many turned to professions such as teaching.

Many of the young men who would later serve in the original 100th Infantry Battalion came from working-class families and left school early to help support their households. For them, completing high school, or even eighth grade, had to suffice. Although only a relatively small portion of the men had attended college, most commonly the University of Hawaiʻi, and even fewer had earned degrees , the soldiers of the 100th would perform remarkably well on Army intelligence examinations, scoring only slightly below the threshold typically required for admission to Officer Candidate School.

As these young men built their lives in Hawaiʻi, events unfolding beyond the islands were steadily drawing the United States toward global conflict.

Global Threats in the 1930s and 1940s

Although the United States had maintained a policy of noninvolvement during much of the 1930s, the rise of the Axis powers became increasingly difficult to ignore. With the growing influence of the Nazi Party, Germany had been aggressively expanding its territory through annexation and military conquest since 1938. In 1940, Italy, under the fascist regime of Benito Mussolini since the 1920s, formally allied itself with Germany.

Japan’s expansionist ambitions, which had been building for decades, intensified with its military aggression in Manchuria and China. As Japan expanded across East Asia and into the Pacific, bringing its forces closer to the Philippines, U.S. leaders feared Hawaiʻi could become its next target.

Rising Suspicion Toward Japanese Residents

Government suspicion about the loyalty of Japanese residents in America increased, especially toward those living on the West Coast of the United States. The atmosphere was also tense in Hawaiʻi, home to the U.S. Navy’s Pacific Fleet at Pearl Harbor.

By 1940, nearly 40 percent of Hawaiʻi’s population was of Japanese ancestry. Authorities were especially concerned about the Issei, who were ineligible for U.S. citizenship and remained citizens of Japan. They were also focused on several thousand Kibei, a term for Americans of Japanese ancestry born in the United States who had spent their formative years in Japan or had been educated there.

Community Leadership and Inclusion Efforts

Despite rumors and growing distrust, several government, military, and civic leaders in Hawaiʻi worked to calm public fears and reassure officials in Washington, D.C., emphasizing the loyalty of the local AJA community and their contributions to island society.

In August 1939, the Federal Bureau of Investigation (FBI) opened a Honolulu office under Special Agent in Charge Robert Shivers, who immediately directed his staff to conduct a comprehensive assessment of internal security conditions in the islands. Working closely with Army and Navy intelligence officials, including Col. George Bicknell of the Army counterespionage section, the FBI investigated Hawaiʻi’s Japanese population. As federal authorities reviewed the backgrounds and activities of individual Nisei, it appeared that there was little reason to doubt the loyalty of the majority of AJA, even as some cases continued to be monitored.

Beginning in 1939, an influential group of civic and community leaders began meeting to promote racial cooperation and advocate for the inclusion of Americans of Japanese ancestry in the war effort. Formally organized in December 1940 as the Council for Interracial Unity, the multiracial group was brought together largely through the efforts of YMCA executive Hung Wai Ching and included educator Shigeo Yoshida, University of Hawaiʻi regent Charles Hemenway, McKinley High School principal Miles Cary, insurance executive Masa Katagiri, attorney Masaji Marumoto, and others. Shivers became chairman of the group and worked closely with its members.

After the outbreak of war, several members of the council, including Ching and Yoshida, served in the Morale Section of the military government alongside officials such as Charles Loomis, helping to maintain public stability and act as liaisons between military authorities and Hawaiʻi’s community. This effort and the role of the Council and Morale Section is discussed in detail in Battle of the Home Front: Inclusion Versus Exclusion by Tom Coffman.

Draft and Military Organization in Hawaiʻi

In anticipation of a likely conflict, the United States enacted the Selective Training and Service Act in September 1940, establishing the first peacetime draft. In the year leading up to the attack on Pearl Harbor, about 3,000 men in Hawaiʻi reported for Army service, most of them drafted, with some volunteering. Approximately half of these men were Americans of Japanese ancestry.

President Franklin D. Roosevelt signed Executive Order 8530 on August 31, 1940, authorizing the federal activation of National Guard units into U.S. Army service. In Hawaiʻi, this process brought the Hawaii National Guard into federal service in October 1940, and the 298th and 299th Infantry Regiments thereafter served as units of the U.S. Army. Inductees were assigned to the 298th Infantry Regiment on Oʻahu or the 299th Infantry Regiment, primarily based on Hawaiʻi, Maui, Kauaʻi, and Molokaʻi. Some men were also assigned to engineer battalions.

Their composition reflected the diverse ethnic backgrounds of Hawaiʻi’s communities, bringing together men of different heritage to serve alongside one another. After completing basic training at Schofield Barracks on Oʻahu, the men were tasked with guarding Hawaiʻi against external threats.

Aware of the prevailing anti-Japanese sentiment, the AJA recruits approached their training and duties with exceptional dedication, prompting Lieutenant General Charles D. Herron, commander of the U.S. Army’s Hawaiian Department, to call them “the best recruits I have ever seen in 45 years.”

Early in 1941, one of FBI agent Shivers’ Nisei advisory groups helped organize the Oʻahu Citizens Committee for Home Defense, composed of AJA. At a large rally sponsored by the committee in June 1941, Lt. Col. M. W. Marston then Assistant Chief of Staff, G-2 (Military Intelligence), Hawaiian Department, U.S. Army, delivered the principal address and publicly praised the loyalty and military service of Hawaiʻi’s Japanese American community. Speaking on behalf of Lt. Gen. Walter C. Short, then commanding general of the Hawaiian Department, Marston pledged fair treatment for all the population in Hawaiʻi, so long as they remained loyal to the United States.

Marston emphasized that “no group of selectees is doing its work with more intelligence, enthusiasm and efficiency than the young men of Japanese ancestry” in Hawai‘i, and described them as “one of our greatest assets whether in peace or war.” He urged attendees to demonstrate their loyalty through national service, declaring, “This is your great chance to convince the rest of the United States that you at least out of the many groups in America have become one with all Americans in the defense of our country and its American ideals. Once you Americans of Japanese ancestry have done this no one will dare to question your place in our community.”