Who had to stay at home and work on the farm in tomorrow when the war began?

In the novel "Tomorrow, When the War Began" by John Marsden, the character Ellie Linton and her friends are primarily high school students who were forced to stay at home and work on their farms when war broke out. This situation arose as they were initially caught off guard while camping in the bush, and upon returning, they found their hometown invaded. While they faced the challenges of adapting to this new reality, their families and the community were also impacted by the conflict.