Diokno and Aquino, whom the dictatorship considered their foremost opponents, were later handcuffed, blindfolded, and transferred via a chopper to solitary confinement at Fort Magsaysay, located in the municipality of Laur, Nueva Ecija. They remained confined to Fort Magsaysay for exactly thirty days. They both learned of each other's presence through singing. One of them would frequently sing the national anthem "Lupang Hinirang" or "Chosen Land", to which the other would reply by singing "Bayan Ko" or "My Country" to prove he was still alive. To tally the number of days, Diokno used knots of ropes from his mosquito net as well as the back of a soap packaging box and crossed out each day in the manner of a calendar. His visiting family members were often strip-searched by soldiers. They would sneak in books in French and Spanish for him to read, and he would converse to his wife in Spanish for only them to comprehend. Diokno would tell his family not to weep in front of the sadistic soldiers. Only his Aunt Paz Wilson, a woman in her 90s and a mother figure since his mother's passing, would frequently cry during every visit. She continued to visit despite also undergoing strip searches. The family would be in tears once they left the prison, where the Aquino family would see them. This helped the Aquinos prepare themselves emotionally since they never saw the Diokno family manifest much pain before. "Nena" Diokno, suspicious of Marcos, took most of her husband's books at the library along M.H. del Pilar and brought them home before the military burned down the library. Jose would thank her as he was very familiar with the library and memorized the location of each shelf and book he read. Outside the prison, Marcos announced at his executive mansion, Malacañang Palace that September 21 would be known as "National Thanksgiving Day", the same day Diokno led his biggest Plaza Miranda rally. This declaration has led to a general confusion about the true date of the public announcement of martial law, which was actually on September 23, two days after Proclamation No. 1081 was signed.