Complex sentence: One of the committee's primary goals was facilitating the further emigration of these refugees, mostly to countries outside of Europe; it is estimated that the Committee assisted about 18,000 refugees in re-emigrating and thus escaping the The Holocaust (1941--1945).
Split into simpler sentences: One of the committee's primary goals had been to facilitate the further emigration of these refugees to countries outside of Europe. It is estimated that the Committee assisted the emigration of about 18,000 refugees, who thus escaped The Holocaust (1941--1945).