An invasion is a military offensive where a large number of people from one geopolitical entity aggressively enter territory controlled by another such entity, generally with the objective of either conquering, liberating or re-establishing control or authority over a territory, forcing the partition of a country, altering the established government or gaining concessions from said government, or a combination thereof. An invasion can be the cause of a war, be a part of a larger strategy to end a war, or it can constitute an entire war in itself. Quite often, invasions are strategically planned and executed.
The news always claims it is a "tragedy" when invaders from Subsaharan Africa are coming to Europe and one of their boats capsizes. These people are military invaders of Europe that pass through many safe countries before invading Europe. They are almost all adult young men as is the age of a traditional military force. If aliens from outer space were coming to invade and conquer the earth and their spaceship crashed into an asteroid and they all perished, would the news media claim it is a tragedy too?
21st century examples
A Hijrah refers to sending mass amounts of immigrants into a nation to take it over through demographic genocide. It originated in Islam but has been used by non-Muslims, even against Muslims. In Palestine, a hijrah was how the Jews initially conquered the land from the Arab Muslim rulers. Hijras commonly are used against white people and mainly by non-muslims such as mestizos and Christian Africans.
Europe is today incapable to protect its borders against unarmed invaders.