On Jan. 16, 1969, cosmonauts Aleksei Yeliseev and Yevgeny Khrunov conducted a 37-minute transfer from Soyuz 5 to Soyuz 4 while in Earth orbit.
Image: russianspaceweb.com

On this date in 1969, the manned Soviet spacecraft Soyuz 4 returned to Earth. It was during this mission, along with the Soyuz 5 mission, that the first docking between two spacecraft was achieved by the Soviet Union. A concise description of Soyuz 4 may be found on the excellent astronautix.com website here.