On August 22, 1956, Chinese fighters shot down U.S. Navy reconnaissance plane over Shegsi Islands, killing all 16 crew members.
Communist China proved that it could be just as aggressive as the Soviets. PRC fighters regularly tailed Naval reconnaissance aircraft and, on occasion, had opened fire, but they did not shoot down an SESP platform until August 22, 1956, when a P4M-1Q Mercator was downed in an unprovoked attack 32 miles off the coast of China and 180 miles north of Taiwan. The aircraft radioed that it had encountered hostile fighters and was not heard from again. All 16 crewmen were missing:

AT2 Donald W. Barber
AO2 Warren E. Caron
AT3 Jack A. Curtis
LTJGJames B. Deane
LTJGFrancis A. Flood, Jr.
AT1 William F.Haskins
AO3 William M. Humbert
LCDR Milton Hutchinson
AD1 Harold E. Lounsbury
AT1 Albert P.Mattin
AT2 Carl E. Messinger
LCDR James W. Ponsford
AE2 Wallace W. Powell
AT3 Donald E. Sprinkle
AT2 Leonard Strykowski
AD3 Lloyd L. Young

08.22.56 USN Recon Plan Shot DownB
The VQ-1 aircraft (BuNo 124362) was lost at night and, despite an intense search and rescue operation, the body of only one of the 16 missing crewmen was recovered by the destroyer USS Dennis J. Buckley (DD 808). The remainder were presumed dead (the PRC would later return the bodies of three crewmen). It was the costliest Naval reconnaissance loss to date. Unfortunately, the secrecy of the mission, combined with the Navy’s lack of hard information about what happened to the aircraft, gave rise to rumors among families and the “secret sailors” of the SESP program that some of the missing aircrew were in Chinese captivity. Yet no credible evidence ever came to light to substantiate such rumors.

Although none of the crewmembers were cryptologists, this unprovoked attack by the PRC needs to be told and remembered.

Source:  A Dangerous Business: The US Navy and National Reconnaissance During the Cold War.”