I think that Gibbon's
History of the Decline and Fall of the Roman Empire should be included. Someone earlier suggested a work of World History, which would definitely be a good idea, but my only problem is that I can't think of one that's actually good enough to earn it's place. Don't know if anyone else has suggestions I'm not aware of.
But Gibbon's book is worth including for several reasons. It's beautifully written and highly engaging to read, and it covers a broad swathe of the history of Europe, North Africa and the Middle East stretching over a period of about 1300 years, which isn't bad going for a history focused on a specific topic.
It also tells us about much more than the Roman Empire. It discusses a lot of ecclesiastical history, for example, and he quotes and summarise large swathes of ancient literature which, obviously, the colonists will not longer have access to - it would give them a glimpse into the world they've lost.
His discussions of controversies current in the 18th century would also give us insights into the intellectual and religious development of Europe long after the period covered in the book.
Now I've written this it all seems very Eurocentric, though. And maybe your only book of history shouldn't be one that describes black people as being intellectually inferior to the rest of mankind. Ten books is hard.