On the morning of June 8, 1920, as the SS Vasna set sail from Bombay’s Ballard Pier, the British colonial authorities breathed a sigh of relief. On board the hospital ship riding the Arabian Sea was a passenger whose demands had become uneasily persistent.

Mirza Ali Muhammad Khan was once the governor of the wealthy province of Bushehr in Iran. He had been exiled to Poona in 1915, in the early days of the First World War, along with his family and a few servants. For the next five years, he stayed unhappily in western Indian city, constantly petitioning the British for money and better living conditions.

When he left from Ballard Pier, on his way to Tehran via Baghdad, he was accompanied by seven men, four women, two children, a car and 60 suitcases. Before the send-off, the authorities made one more accommodation request.

In a telegram to the British Political Resident in Baghdad, the Indian Foreign Secretary wrote, “[The] government of India will be grateful if you will consider whether any courtesies are desirable and can afford him facilities for the onward journey.”

Located at the intersection of India, Afghanistan and the Ottoman Empire, Iran was in a precarious geopolitical position in the early 20th century....