The medal's obverse bears bust of Abraham Lincoln facing right. Around, ABRAHAM LINCOLN PRESIDENT UNITED STATES.; signed under truncation, BARBER
The reverse bears stylized wreath with legend, MARCH 4. 1861 / TO / APRIL 15. 1865. / EMANCIPATION / PROCLAIMED / JAN. 1. 1863.; in exergue, MEDAL SERIES OF THE / U.S. MINT. / J. POLLOCK - 1871- DIRECTOR
This handsome medal can be seen as an expression of gratitude from Mint director James Pollock to his friend Abraham Lincoln. Not only did they serve in Congress together, but they also boarded at the same boardinghouse! When Pollock retired from Congress, Lincoln appointed him Director of the U.S. Mint.
The circular medal measures 45mm in diameter and was struck in bronze by the U.S. Mint in the years between 1871 and 1904. A total of 363 pieces were struck in that period,155 of them in 1872 alone. The medal is usually identified as Julian CM-16.
Most of the information on this medal came from John Kraljevich's website.