Complex sentence: In 1855 just 1250 Imperial troops, from two under-strength British regiments, were in New Zealand and Browne was able to retain one of those on the eve of its scheduled departure for use in New Plymouth, where settlers feared the spread of inter-tribal violence.
Split into simpler sentences: In 1855 just 1250 Imperial troops, from two under-strength British regiments, were in New Zealand. Although both were scheduled to depart, Browne was able to retain one of them for use in New Plymouth, where settlers feared the spread of inter-tribal violence.