It will help to know something of Tennyson and the period in which he lived.
Alfred, Lord Tennyson was one of the most important poets of the Victorian period. He was the Poet Laureate (the country's official poet) from 1850 until his death in 1892. His poems range from those focused on the legend of King Arthur to those dealing with the loss of a loved one.
The Crimean War took place between 1853 and 1856, with Imperial Russia on one side and an alliance including Britain and France on the other. The poem takes as its subject the Battle of Balaclava, one of the many battles of the war.