Joseph Dekalo is the youngest child of Moise Dekalo (b. 1888, Haskovo) and Fortuna nee Mefano (b. 1898, Yampol). Joseph was born on October 5, 1925 in Haskovo Bulgaria. He had a sister Bella (b. 1919) and a brother Jules (Judah) b. 1921. Moise was an importer and exporter of leather; the family was assimilated but kept kosher and attended synagogue on holidays. In 1933 the family moved to Sofia. Jules attended the French College, and Joseph and Bella went of the best school in the city. Joseph also belonged to the Betar Zionist youth movement where he first met Dora Levy. In July 1940, Bulgaria instituted anti-Jewish legislation, and the following year Jules was sent to forced labor building roads. He worked on a labor brigade for the next three years, but he could return home occasionally for visits. Though the Bulgarian government never deported its Jews to concentration camps, in 1943 it expelled all the Jews from Sofia. The Dekalo family was sent to Stara Zagora in the south where they remained for three to four months in a rented apartment. From there they were relocated to Lucovit, where they remained until the end of the war together with some 120-130 other families. The community was organized and took care of each other and even set up a communal kitchen. Jews were required to wear the Star of David and could not work, but Joseph was able to attend high school. Joseph's aunt had to sell her clothes to provide for herself. After the war the family returned to Sofia.
Dora Levy was born in 1926 in Sofia. She had two brothers who were much older: Moise was 16 years older and Leon was 18 years older. Her father Avraham died when she was young, and her brothers helped care for her and run their father's store. Dora could only attend high school for one year since she had to work, but she joined the Betar youth movement where she met Joseph. After her brothers were sent to forced labor, Dora remained at home with her sisters-in-law and mother. In 1943 they were expelled from Sofia and went to Stara Zagora. Dora reunited briefly with Joseph, but then her family had to relocate to Razgrad near the Romanian border. Joseph wanted her to remain with him, but she did not want to leave her mother. In Razgrad she worked the fields gathering vegetables to earn some money, and the local Jewish community also supported the refugees. At the end of 1944 they were told that they had to leave and would be sent to Poland. They were put on cattle cars, but after two days were released. They returned to Razgrad where they were liberated by the Russians. Afterwards Dora returned to Sofia and reunited with Joseph.
Joseph and Dora joined a Betar group headed by Sarika Levy (later Shulamith Shamir, wife of the Israeli Prime Minister Yitzchak Shamir). Joseph finished high school in Sofia and studied law for one year. However, they wanted to immigrate to Palestine. On November 12, 1946 Joseph and Dora married in a private a civil ceremony. They did not tell their parents; only their siblings knew. After some problems they crossed the border into Romania and stayed in Bucharest with friends from Betar. They remained in Bucharest for eight and a half months supported by the Joint Distribution Committee. From Bucharest they went to Vienna where they stayed in the Rothschild Hospital. From there they went to Marseilles and joined an Etzel group headed to Italy. They were on route for 18 months during which time they had occasional communication with their parents. In June 1948 they boarded the Altalena. They first lived in new immigrant camps and then went to live with Joseph's uncle in Herzelia. Joseph participated in the War for Independence and then worked in the construction business eventually starting his own small company doing small renovations.