The 2013 Children/Children's camp attended by 56 children was held successfully...

[Tan Elaine]

The 2013 Children/Children's camp attended by 56 children was held successfully last year.

Which bold word should I use? Thanks.

 

[MikeNewYork]

The 2013 Children/Children's camp attended by 56 children was held successfully last year.

Which bold word should I use? Thanks.

I would use the possessive.

 

[Tdol]

It's not a very natural sentence, though. As we're in 2014, the last year part doesn't add much because we already have the date.

 

[emsr2d2]

It's not a very natural sentence, though. As we're in 2014, the last year part doesn't add much because we already have the date.

I agree but leaving "The 2013 Children's camp attended by 56 children was held successfully" is also unnatural. I would reword it as something like "The 2013 Children's Camp was very successful - 56 children attended".