Simplify the following text for a Grade 9 native English-speaking person.
Original: The Italian campaign refers to a series of battles fought between the armies of Austria-Hungary and Italy , along with their allies , in northern Italy between 1915 and 1918 .
Simplified: The Italian campaign was a series of battles fought between Austria-Hungary and Italy . These battles happened in northern Italy between the years 1915 and 1918 .