Yes. First the British called on the Germans to withdraw from Belgium, and set a deadline. When the Germans did not withdraw the British entered the war.
Britain and Germany (actually Prussia, of which Germany was a successor state) were two of four Great Powers pledged in an 1839 Treaty to perpetually respect and defend Belgian neutrality. German war plans for a generation had cynically disregarded this Treaty obligation in their scheme to outflank French border defenses by going through Belgium. When Britain raised the issue of the Treaty in demanding German withdrawal from Belgium, the German Foreign Minister denounced the Treaty as " a scrap of paper".
German troops crossed through Belgium in an attempt to flank the French forces lined in trenches along the border.
German invasion of Belgium, Netherlands, and Luxembourg.
Poland :<
The British were call redcoats, lobsterbacks, regulars and bloodybacks
During World War II itself, German troops crossed the borders into numerous countries, both in Western Europe and in Eastern Europe (not to overlook their North African campaign). Perhaps the most significant border-crossings occurred in September of 1939, when the war began after Germany violated the Polish border, and in June of 1941, when Germany crossed the border of their "ally," the Soviet Union, and thereby ensured their ultimate defeat in the war.
German troops crossed through Belgium in an attempt to flank the French forces lined in trenches along the border.
Because German troops had crossed the border into Belgium, contravening a longstanding treaty that guaranteed Belgian neutrality.
On the Allied side. There were French and British troops alongside the Belgians trying to repel German invaders.
German invasion of Belgium, Netherlands, and Luxembourg.
The evacuation of 338000, mostly British troops, following the German Army's brilliant tactical advance through Belgium and France in 1940.
Poland :<
WW2 began when German troops invaded Poland.
George Washington and the American Army
Hessians.
poland.
George Washington
They crossed the Delaware River on Christmas Eve, to catch the Hessians and British troops off guard. This was the battle of Trenton.