The phrase "assertion of what" is correct and usable in written English.
It can be used when discussing the specific content or subject matter of an assertion or claim being made.
Example: "The assertion of what he claimed during the meeting was later challenged by the evidence presented."
Alternatives: "claim of what" or "statement of what".
We do not impugn appellant's good faith in the assertion of what he believed to be his rights.
Rather, the new paradigm seems to be the Asian assertion of what Dr. Mahathir called European values.
His letter was welcome as an assertion of what Mr. Bush says are his true racial and religious values.
In his famous book "Mere Christianity," adapted from a series of BBC radio talks during World War II, Lewis laid out a clear assertion of what it meant to be Christian.
Pippa Virdee, a senior lecturer on South Asian History at De Montfort University, says: "There has generally been a greater assertion of what it is to be Sikh in the last 10 to 15 years.
The slogan is an angry assertion of what should be the case but isn't, as open markets and cheap labour from eastern Europe allegedly cut a swath through traditional French life.
He made sweeping assertions of what he could do, powered — not inhibited — by the objections of realists.
He might have been more specific initially, not leaving himself open to Mr. Chico's assertions of what he'd cover, in turn prompting Mr. Emanuel's denials.
"If there are simply a bunch of vague assertions of what might happen -- that is not as compelling as if there were a significant set of understandings to be achieved".
To quote the Prologue again, "while our actual knowledge is incommensurable with the greatest knowledge, something humanly unattainable, the unsure falling away of our weak apprehension from the purity of truth makes our assertions of what is true conjecture".
Shooting down their hyperbolic assertions of what will happen if A.B. 1266 stays in place can easily be done in a 10-second sound bite.
