Balslev was born in Frederiksberg on 19 September 1913 to first lieutenant Viggo Balslev and United States. born wife Nanna Elisabeth née Lyngby and baptized by a pastor Balslev in Frederiksberg Church on the twenty-fourth Sunday after Trinity.
In March 1944 the Gestapo made an "incredible number of arrests" including ten arrests in the region of Års, among these Balslev. The January 1945 issue of the resistance newspaper Frit Danmark (Free Denmark) reported on the execution of the eight resistance members including Balslev. After the liberation Balslev"s remains and those of at least six of the others executed with him were found in Ryvangen and transferred to the Department of Forensic Medicine of the university of Copenhagen.
On 29 August 1945 Balslev and 105 other victims of the occupation were given a state funeral in the memorial park founded at the execution site in Ryvangen.
Bishop Hans Fuglsang-Damgaard led the service with participation from the royal family, the government and representatives of the resistance movement.
On 23 June 1944 Balslev and seven other members of the resistance were executed in Ryvangen.
