[quote=Jannah]
I still have to choose an era, damn T_T.
[/quote]

Some random idea:
Prehistory; write about the first man discovering fire, hunting wildlife to feed his tribe, fight a nearby hostile tribe...
Middle ages: Enough to write about here. Royalty, knighthood, wars, crusades, crusades from the other side.
Semi-modern history: The forming of the United States, renaissance...
Modern history: The forming of the EU, the falling apart of the USSR. Alternatively, pick a random war from the last two decades or so. For bonus points, try to write from the other side's perspective.