Poland had fallen under the power of the Tsars in 1815.
Poland did not become a full part of the Russian Empire but instead had nominal independence even though the Tsar was King of Poland.
In 1831, the Poles rebelled against Nicholas I but the revolt failed and the Tsar restricted Polish freedom.
When Alexander II became Tsar in 1855, he made conciliatory gestures towards the Poles.
However, the Polish ambition for independence was strong.
In response to nationalist demonstrations in Warsaw in 1861, Alexander II introduced further reforms such as opening a new university in the Polish capital.
Polish nationalism continued to grow and by January 1863, there was an armed rebellion.
The rebellion took over a year to suppress.
Alexander II was disillusioned that his attempt at reform and conciliation towards the Poles had been met with such retaliation and hostility.