Soon after his arrival in Danzig however, R' David left to Vilna, the home of many distinguished Torah scholars, and soon traveled to learn in Ponevezh Yeshiva.

He wrote his first sefer, Tzemach David, a work in which he provided answers for many of the difficulties of Rabbi Akiva Eiger, around that time.

Soon after, Rabbi Rappoport wrote his second sefer, titled Mikdash David, which consisted of five volumes (four of which survived World War II).

[5] With the outbreak of World War II, the yeshiva escaped Poland to Vilna, and then to Troki and Smilishoki.

On June 21, 1941, which was a Shabbos Parshas Shelach, he was arrested by the Communists and sentenced to forced labor in a remote Russian concentration camp in Medvezhegorsk, near the Russian-Finnish border.