Sidney (Yeshayahu) Rubinoff was born on February 21, 1926 in Toronto, Canada to Menachem and Matilda. His family was mostly composed of immigrants. During his youth the family was twice evicted from their home when they were unable to pay the rent, and this had a lasting effect on Sidney.
At the age of 18 he was drafted into the Canadian army and reached Europe towards the end of World War II. His meeting with the surviving remnants of European Jewry made an indelible impression upon him.
With the outbreak of the War of Independence he was among the first foreigners to volunteer to fight with the Palmach, reaching Haifa before the city was liberated. After taking part in numerous battles he was fatally wounded in the battle for Latrun on July 14, 1948. He was buried in the military cemetery in Nachlat Yitzhak.