Is it the Hat or Just Pure Luck?

My Great Grandfather, Dr. David Hermoni, the first Head of the Hadassah Hospital Blood Bank in Jerusalem, always wore a white lab coat and a hat.
On April 13, 1948, he was supposed to be a doctor riding on the Mount Scopus Convoy, bringing aid to Hadassah Hospital and the Hebrew University, Mount Scopus. This was as tensions were growing, just as Israel was about to declare its independence, and traveling in convoys was the only solution to bring doctors, nurses, and supplies safely to the Hospital. He was about to board, when he remembered that he forgot his hat and ran back home to get it. When he returned, the convoy was full, and a supervisor sent him home. Later that night, the convoy was attacked by Arab forces and 78 Jewish students, doctors, Hadassah faculty members, nurses, and one British soldier were massacred. And my great grandfather, a bald man who had forgotten his hat, was saved and he was able to be with his wife when she gave birth to my grandfather, who was born on the same day as the Jewish state, 14 in May 1948.

So, was it pure luck or a lucky hat that saved my great grandfather's life?