Invasion.
Poland
German troops invaded Poland, so the Polish border.
Immigrants cross the border for numerous reasons, including famine, war, drought or persecution in their own countries or to get better jobs, housing or medical services.
They were called border states
By having Mexico start the war by driving the Mexican forces out of the disputed border region in Texas & make the border secure.
The Mexican American War, the Indian Wars and it was also involved in the Mexican Revolution involving the cross border attacks by Pancho Villa.
Canada
"We didn't cross the border; the border crossed us." (APEX)
Thick forests covered much of the border; the rugged Vosges Mountains formed the rest of the border. This made the border hard to cross. -WORLD GEOGRAPHY & CULTURES TEXTBOOK
No they did not fight in the war. They took care of the soldiers in the war. Where they worked was called the Red Cross.
Brutal, conflicts, conhfrontation, cross border attacks, on the verge of war
The border states were called so because they were situated on the border between the Union (North) and the Confederacy (South) during the American Civil War. These states were Kentucky, Maryland, Missouri, and Delaware. They were crucial because they had strategic significance and their allegiance could have tipped the balance of power in the war.