His time as Grand Prior came while he was a rather busy Bishop. He served as Bishop of Essen, attended the second Vatican council in 1962-65 and Served as Grand Prior concurrently.
In 1954 he was appointed Knight of the Order of the Knights of the Holy Sepulcher by Cardinal Grand Master Nicola Cardinal Canali and invested on December 8, 1954 in the Church of St. Andrew's Basilica by Lorenz Jaeger , Grand Prior of the German Lieutenancy ; last in the rank of Grand Cross Knight .
From 1975 to 1991 he was Grand Prior of the German Lieutenancy of the Knightly Order of the Holy Sepulcher in Jerusalem.
For his work in the Holy Land, he was awarded the Golden Palm of Jerusalem by Cardinal Grand Master Maximilien de Fürstenberg in 1979 .
Wikipedia has some information, but it is not very detailed:
"Franz Hengsbach was born in Velmede to Johann and Theresia Hengsbach; he had five brothers and two sisters. He studied at the Institute of Brilon and the seminaries in Paderborn and Freiburg. Hengsbach obtained his doctorate in theology in 1944 from the University of Münich, with a dissertation entitled Das Wesen der Verkündigung - Eine homiletische Untersuchung auf paulinischer Grundlag.
He was ordained to the priesthood by Archbishop Kaspar Klein on 13 March 1937, and then served as vicar of Herne-Bukau, St. Marien until 1946. Hengsbach became general secretary of the Akademische Bonifatius-Vereinigung in Paderborn in 1946, and of the Central Committee for the Preparation of German Catholics in 1947. From 1948 to 1958, he was director of the archdiocesan pastoral office of Paderborn. He was made Domestic Prelate of His Holiness in 1952, and secretary general of the Central Committee of German Catholics on 30 April 1952.
On 20 August 1953 Hengsbach was appointed Auxiliary Bishop of Paderborn and Titular Bishop of Cantanus by Pope Pius XI. He received his episcopal consecration on the following 29 September from Archbishop Lorenz Jäger, with Bishops Wilhelm Weskamm and Friedrich Rintelen serving as co-consecrators, in Paderborn Cathedral. Hengsbach was later named the first Bishop of Essen on 18 November 1957. The Bishop later founded Adveniat, an organization of the German episcopate to assist the Roman Catholic Church in Latin America, and was appointed bishop of the German Military Ordinariate on 10 October 1961. From 1962 to 1965, he attended the Second Vatican Council. Hengsbach also served as Grand Prior of the Equestrian Order of the Holy Sepulchre of Jerusalem, and was made President of the German Episcopal Commission for Universal Church Affairs in 1976. He was appointed a member of the Council of the European Episcopal Conference in 1977, and resigned from his post in the military ordinariate on 22 May 1978.
Pope John Paul II created him Cardinal Priest of Nostra Signora di Guadalupe a Monte Mario in the consistory of 28 June 1988. Hengsbach lost the right to participate in any future papal conclave upon reaching the age of eighty on 10 September 1990 and, after a period of thirty-three years, resigned as Bishop of Essen on 21 February 1991.
The Cardinal died from complications after a stomach operation at an Essen hospital, aged 80. He is buried in the crypt of Essen Cathedral. "
The order he served in is also described in Wikipedia:
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