During what time period was the greatest share of territory unified in italy?

Hello there! :)

I personally didn't know the answer to this question, but I looked it up out of curiosity: 
"By the early 19th century, a nationalist movement developed and led to the reunification of Italy--except for Rome--in the 1860s. In 1861, Victor Emmanuel II of the House of Savoy was proclaimed King of Italy. Rome was incorporated in 1870."

I hope this helps :). 

A. southerners underestimated republicans eagerness to end slavery.