Rosenberg was assigned to the 12th Bantam Battalion of the Suffolk Regiment, a "bantam" being a designation for men under the usual minimum height of 5'3". After apparently declining a promotion to lance corporal, Rosenberg was transferred, first, to the South Lancashire Regiment, then to the King's Own Royal Lancaster Regiment. He was sent with his unit to serve on the Western Front in France, where he arrived on 3 June 1916. He continued to write poetry while serving in the trenches, including "Break of Day in the Trenches", "Returning We Hear the Larks", and "Dead Man's Dump". In December 1916, "Poetry" Magazine published two of his poems.