Historical documents have revealed that Benzion Netanyahu, Prime Minister Benjamin Netnayahu's late father, warned of the dangers of the Nazi annexation of Austria (known as the Anschluss) two months before it happened. According to the documents, Alexander Aaronsohn, co-founder of the Jewish underground spy network Nili, asked Netanyahu on Jan. 31, 1938 if it would be wiser to concentrate diplomatic efforts on benefitting the Jews of Austria or on preventing the Anschluss. Netanyahu warned that in his opinion, doing everything possible to prevent the Anschluss was the priority. Adolf Hitler annexed Austria to the Third Reich on Mar. 12, 1938, two months after the conversation between Aaronsohn and Netanyahu. With the annexation, Austria became a German province, a move that was not stopped by world powers. It was a crucial step toward the outbreak of World War II and the Holocaust. The document revealing Netanyahu's insight was presented to his son, the prime minister, during a visit on Monday at the Nili Museum in Zichron Yaakov. The museum staff further presented the prime minister with a number of other documents related to his father. One of the documents was a letter of recommendation for Netanyahu, written by poet Shaul Tchernichovsky to Aaronsohn. "Your honor, I recommend having a conversation with Mr. B. Netanyahu, former editor of the daily newspaper 'HaYarden,' and current editor of the '[Zionist] Political Library,' which has published the works of [Zionist leaders Max] Nordau and [Theodor] Herzl, on matters related to literary recommendation." Tchernichovsky, who knew Netanyahu since he was co-editor of Hebrew literary monthly Betar, continued: "I am sure that this conversation would bring about great benefit."