Howling:What's the connection between the Big Bads?

So, in Series 6, it was The Silence going to great lengths (maybe even causing the TARDIS to explode in Series 5) to prevent The Doctor from being "on the fields of Trenzalor at the fall of the Eleventh". Nevermind that it didn't look like there were any fields there, in The Name of the Doctor (TV story), Moffat put together some kind of alliance between The Great Intelligence and The Whispermen...I s suppose that snowmen were no longer available on a planet that looks volcanic? I'm guessing that that The Whispermen have nothing against The Doctor and are just agents of the Great Intelligence like The Silence had creatures/people working on its behalf.

So what is the connection between the Great Intelligence and the Silence? Moffat could have picked any location forThe Name of the Doctor (TV story) but he chose Trenzalor so there must be some link. However, The GI and The Silence seem to have two different agendas....The Silence need to prevent their "fall" and The GI seems to be seeking power or the intelligence and experience gained by The Doctor over his lifetime (I'll need to see the episode again to be sure).

All along, I assumed that Moffat would bring The Doctor to Trenzalor when Matt Snith wanted to leave and it was time for a regeneration and a new Doctor (hence, "the fall of the Eleventh"). But, no, he brought him there way before this.

So do any of you clever people see any connection between The GI, The Whispermen and The Silence and the pivotal role of Trenzalore in the missions of both groups?