Samuel Tom Holiday, one of the last living Navajo Code Talkers from World War II, died Monday. He was 94.

Holiday was one of hundreds of Navajos who used their native language to create and maintain an unbreakable code in an effort to win World War II, according to the Associated Press.

Holiday, who turned 94 on June 2, joined the Marine Corps at 19.

During the war, Holiday served with the 25th Marine Regiment, 4th Marine Division and participated in operations in various locations in the Pacific, including Kwajalein, Saipan, Tinian and Iwo Jima, according to AP.

The operation wasn’t declassified until 1968, but code talkers were considered essential to the US war effort.

During his time in combat, Holiday was injured by an exploding mortar, which hindered his hearing for the rest of his life. Holiday later received a Congressional Silver Medal and a Purple Heart, according to the Associated Press.

After returning home, Holiday worked on the Navajo Reservation as a Navajo police officer and a ranger before he started his own heavy-equipment company.

In 2013, Holiday wrote the book, “Under the Eagle: Samuel Holiday, Navajo Code Talker,” with Robert S McPherson. It was published later that year by the University of Oklahoma Press.

In 2017, Holiday told Spectrum that he was mistaken for a Japanese soldier during the war by his fellow American soldiers. However, he said his dedication to the cause never wavered despite these discouraging incidents.

Holiday married his late wife, Luipta Maie Isaac, in 1954 and had seven daughters and one son. According to Spectrum, as of 2017, there were 78 members and counting of Holiday’s extended family.

Holiday passed away with friends and family at his side while in hospice care at the Southern Utah Veterans Home in Ivins, Utah, AP reported.

Friends and family that started a GoFundMe in order to pay for their travels to see Holiday. The GoFundMe is still active, as his family still seeks money to help family members travel to Holiday’s funeral services and to help offset the cost of the services.

According to his family, Holiday will be buried on the Navajo Reservation in Kayenta, Arizona, and will be laid to rest next to his wife.

Navajo leaders believe fewer than 10 Code Talkers remain alive today, according to the Associated Press.