Perhaps you should try some spelling variations:
"american colonial empire" » "american colonization empire"
"american colonial empires" » "american colonization empires"
"american colonies empire" » "american coloured empire", "american colonialism empire", "american colonies exposed"

You may be able to get more results by adjusting your search query.

• If you are trying to use Boolean operators, they must be ALL CAPS: (((("american colonial empire") OR ("american colonial empires"))) OR ("american colonies empire")).
• The words AND, OR and NOT may confuse the search; try adding quotes: "((((\"american colonial empire\") OR (\"american colonial empires\"))) or (\"american colonies empire\"))".
• Removing quotes may allow a broader search: (((( american colonial empire ) OR ( american colonial empires ))) or ( american colonies empire )).
• Adding a wildcard symbol may retrieve word variants: (((("american colonial empire") OR ("american colonial empires"))) or ("american colonies empire"))*.