Conquer

Conquer

Hi,
Something Strange Happened For me When I Was try to Conquer a City
There Was A City in our island and the city's point was 4160
And my city's point was 3994,my friends attacked him and when his city was cleaned I attack him with Conquest and after I won the battle the revolt started.
In the first 12 hours we attacked him for couple a time,and we didn't let him to build up an army.
And when the second 12 hours started I send my CS with a lot troops and light ships and exactly 1 minute before my CS arrive,my friends attacked him with land and sea to make sure he hasn't any troops and ships,and they cleaned his city 1 minute before my cs arrive,but when my cs arrive he destroyed my cs my troops my transports and my light ships and he did all these with just some question mark.
In report there was just a question mark which defeated my units.
And I build another cs,and attacked him again and before send it, there wasn't any ships and troops and then I send my cs again and 12 hours wasn't finished yet and question mark defeat my units and my cs again.

It was my first city which I tried to take it, and my culture points was 2
But he had 2 cities (if these info can help you)

Please tell why this happened,I really confused,Was it a bug or something,be cause I'm sure he doesn't have any units to defeat my cs and...