Kammala jumla mai zuwa: A farkon shekarar 1958, Dag Hammarskjöld ya nada von Horn a matsayin shugaban Kungiyar Kula da Yarjejeniya ta Majalisar Dinkin Duniya a Falasdinu, sannan kuma aka daukaka shi zuwa Manjo Janar. Da farko ya bar kansa "ya kasance mai kyakkyawan fata" kuma ya rubuta a cikin litattafansa cewa "maimakon sojoji masu cikakken makamai, tankuna da bindigogi ko ma barazanar takunkumi, goyon bayan Dag da ƙudurin kaina shine duk abin da nake da shi". A cikin 1960 ya zama babban kwamandan rundunar Majalisar Dinkin Duniya a Congo a farkon abin da zai bunkasa cikin
An sallame shi daga wata shida bayan haka. von Horn ya koma aiki ga Majalisar Dinkin Duniya a Falasdinu. A shekarar 1963 aka tura shi don jagorantar kungiyar lura da Majalisar Dinkin Duniya ta Majalisar Dinkin Duniya a Yemen, inda aka ci gaba da fada tsakanin sojojin gwamnati da 'yan tawaye.