In 1927, when the guerrilla leader, Augusto César Sandino came to San Rafael del Norte, during the Constitutionalist War, he established his headquarters in the telegraph office, which was directly across the street from the American marine's headquarters. Because of the location, Aráuz was able to monitor the American forces' movements and advise Sandino. She was also known to intercept messages and send misinformation, becoming a valuable link in the intelligence service for the Army in Defense of the National Sovereignty of Nicaragua (). The two spent long hours collaborating on a plan to capture the city of Jinotega and simultaneously send forces to assist General José María Moncada. Working closely together, Aráuz and Sandino fell in love and were married in a religious ceremony on 19 May 1927. Within two days, Sandino returned to the front and Aráuz returned to her work in the telegraph office tracking the enemy troops and the nationals who collaborated with them. Periodically, she would live with Sandino in the camps, though travel was difficult.