He studied law in Istanbul

The leadership of Poale Zion determined that "Ottomanization" was the way of the future in the spring of 1911, in response to the collapse of the Second Aliyah. Israel Shochat, Manya, and Ben Zvi declared their plan to relocate to Istanbul. Ben Gurion intended to study law with Ben Zvi and Shochat, but he first needed to learn Turkish. He took lessons with a law student named Joseph Strumsa and learned the language in less than eight months. He did this to get ready for his legal studies. He studied law in Istanbul a year later, in 1912. Due to local Sephardic prejudice, he must keep his Ashkenazi heritage a secret while conducting research. So that Ben Gurion might enroll with him at Istanbul University, Ben Zvi obtained a false high school diploma. In order to avoid budgetary restrictions, he registered at the university as David Gruen Efendi. While Ben Zvi got employment as a teacher, Ben Gurion was entirely reliant on his father for financial support. Ben Gurion spent some time in the hospital while managing his ill health.

When World War I broke out, Ben-Gurion was in Istanbul pursuing a legal education. Along with many other prominent Jews, Ben-Gurion was banished from Turkey by the Ottoman government. He married a Zionist named Paula Monbesz and served in the American military for a while. It is also considered one of the interesting facts about David Ben-Gurion.