Proof that persistence is not sufficient.

There are any number of sites on the internet that give friendly, useful, and accurate advice on how to get published. AbsoluteWrite, for example, has a wealth of information threaded through their forums.

There are also a number of sites detailing why publishers reject submissions. The most enlightening of these is probably Slushkiller by the estimable Teresa Neilsen Hayden.

Much of the advice given in pages like the ones linked to above seems fairly basic. For example, in Slushkiller, Teresa Neilsen Hayden gives the second reason for rejection as:

Author has submitted some variety of literature we don’t publish: poetry, religious revelation, political rant, illustrated fanfic, etc.

Now, I would have thought that much was obvious. If you're trying to sell a military science fiction novel, then it would probably be a good idea to send it to publishers which publish military science fiction novels, as they will quite possibly be more interested in it than a publisher which exclusively publishes, say, Afghan recipes for goat.

However, it appears that I underestimated the depths which human stupidity can plumb--once it really sets its mind to it.

You can read why here.