THEY SERVED IN SILENCE

The Story of a Cryptologic Hero

CPT John M. Casey

...Jack Casey and I got to ‘Nam about the same time - He was a LT and 

I was a PFC. We were both at HHC, 313th RR Bn, Nha Trang. Although 

the Army maintained *on-paper) a rule that officers and enlisted were 

not supposed to “fraternize,” that rule fell apart for most of the Army 

Security Agency troops... We went separate ways later in 1967. I didn’t 

know he was killed until after I got back to the States. Jack was a good 

man. He is missed....

 Fellow Soldier and Friend, Steve Zawacki

CPT. John M. Casey was born on June 5, 1944, in Sparta, Tennessee. Located on the banks of the Calfkiller 

River, the city was named after the ancient Greek city-state of Sparta and since 1806 has served as the 

county seat for White County. John attended the local schools and graduated from White County High 

School in 1962. Later that year, he entered Middle Tennessee State University, but eventually left to attend 

the U.S. Army Officer Candidate School at Ft. Benning, Georgia. After commissioning, he was assigned to 

the Army Security Agency (ASA), the cryptologic element of the U.S. Army during the Vietnam era. After 

training he was certified as an Electronic Cryptologic Warfare Officer. In this capacity he utilized a variety 

of technical tools and methods to control the electromagnetic spectrum to both protect friendly critical 

communications and thwart those of the enemy. 

Spring of 1968 found him in Vietnam, assigned to the 371st Radio Research Battalion at Camp Evans 

just north of the old imperial capital of Hue. John had previously served one tour in Vietnam, and had 

volunteered for another with the 371st. Established in the early ’60s, the unit was originally based in 

Germany, but by 1968 it was fully engaged in providing combat support to the 1st Cavalry in the triple 

canopy jungles of Indochina. During his time “in country,” John worked hard on a daily basis to give the 

troops in harm’s way the cryptologic support they needed to succeed in the battle space, but by March 

of ’68, his time in Vietnam was coming to a close. He was due to report to the Washington D.C. National 

Guard on April 1, but had requested a 30-day delay in his reporting date.

Due largely to the Tet Offensive and its aftermath, 1968 had proved to be a dangerous year in John’s 

area of operation. The attacks that had begun in earnest in January had not abated, and by March, some 

wondered if the nightly Viet Cong mortar and rocket-propelled grenade attacks would ever end. The 

attacks were particularly deadly in that they were often so swift and sudden that soldiers had little chance 

to take appropriate cover. 

This scenario played out on the late evening of March 25, 1968, when, seemingly out 

of nowhere, the base came under an abrupt mortar assault. Despite the danger, John 

moved quickly to rouse his men and get them into a nearby bunker for protection. His 

efforts proved successful in that the majority of the soldiers were able to make it to safe 

spaces. However, while attempting to save his men’s lives, John was felled by a mortar 

round and perished. 
MP 233610

John’s tragic death was mourned by family, and friends and by those who served with him. Bill Rupp, a 

fellow soldier, wrote a tribute to him on an ASA virtual tribute site, “Big John, We traveled from Ft. Devens, 

to end up in Vietnam together. We went to OCS and became officers. I still remember the morning I got 

the call that you were KIA, I still deal with the guilt. I miss you every day. I named my son after you. He 

was born on September 1, 1969. His name is Casey William Rupp. Every time I speak his name I think of 

you He could not have a prouder and respectful first name. You live on.” 

Doug Nelson, another fellow soldier, remembered, “Captain Casey did not reach the safety of the bunker 

he helped us build, in time. I remember him, ordering us, to take cover. He didn’t create this crazy mess, 

in which we found ourselves, but he showed us, how, to live in it.” 

In 2009, another admirer perhaps said it best, “May your spirit, always live on, in the hearts of those, you 

loved and in those who grew to love you for your ultimate sacrifice, courage and dedication.” 

John is buried at Highland Cemetery in his hometown of Sparta, TN.