1941. Philatelic Exhibition in Slavonski Brod. As stamps for the Zagreb Philatelic Exhibition but with colours reversed. 1.50 D + 1.50 D blue-black and 4D + 3D deep brown, comb perf. 11 1/2, tied to a large part of specially prepared FDC with fine strike on the illustrated FD postmark (roman letters only) ”ZAGREB I, ZA PROPAGANDU U POKRAJINI * HFS 13.IV.1941” (”For the Promotion of Philately in the Region”) Signed Schlenger. NB. The exhibition never took place due to the outbreak of war in Yugoslavia on 6th April 1941, followed ny Croatia declaring independence on 10 April.