In Memoriam is Tennyson's elegiac tribute to his friend Arthur Henry Hallam, who died in 1833 at the age of 22. Tennyson wrote this long poem over 17 years as a chronicle of his mourning process. The poem became a favorite of Queen Victoria when she was grieving for her husband, and was one of the most popular and artistically influential poems of the Victorian period. (Summary by gloriana).
