S. Isaac, Campbell & Co.
Saul Issac was a contract equipment maker for the British Army. This style pack saw wide usage in a Crimean War as well as campaigns throughout India and China. Campbell was one of the largest producers of goods that were made to run the Union naval blockade of the Confederacy. This pack was also purchased in the North, where it was issued to several states militia regiments.

The British War Department passed information concerning  any regulation or equipment changes by way of what was called a Circular Letter,      The  Circular of October 3rd. 1854 described and illustrated a new pattern of knapsack 15×12.5 x3 inches .  In 1856 a wooden stick, varnished, and sometimes painted black with a leather guard  strip were added to the top of the pack and the Y straps in white and black leather were made removable along with other small alterations to the design. this was the last pattern used until 1870.

Source:      Soldiers’ Accoutrements of the British Army 1750-1900.    Pierre Turner