On 29 June 1913, the Tsardom of Bulgaria declared war on Greece, thus starting the Second Balkan War. On 4 July, Romania entered the war, allying itself with Greece. The war, which lasted a little over a month, was worsened by a cholera epidemic. Marie would look upon her first encounter with an epidemic as a turning point in her life. With the help of Dr. Ioan Cantacuzino and Sister Pucci, a Red Cross nurse, Marie travelled between Romania and Bulgaria, lending a helping hand in hospitals. These events would prepare her for her experiences in the Great War. As a result of the war, Romania gained possession of Southern Dobrudja, including the coastal town of Balchik (Balcic), which Marie would come to cherish in 1924 and use to host her residence, called The Quiet Nest. Soon after the war ended, Carol became ill.
