The phrase "also to assert" is correct and usable in written English.
It can be used when you want to indicate an additional action of stating or affirming something alongside other actions or points being made.
Example: "In addition to providing evidence, the researcher aims also to assert the validity of the theory."
Alternatives: "also to claim" or "also to state".
Dr. Edgar said it was no coincidence that South Carolina was the first state to secede in 1861, partly to preserve slavery but also to assert its independence from Washington.
Yet the most wily diplomat of the age, Ferdinand II (the Catholic) of Aragon, the king of Spain, hoped not only to forestall French ascendancy and outsmart Louis XII in Italy but also to assert his own claims as the legitimate heir to the Aragonese empire founded by Alfonso V (the Magnanimous) in 1442.
Their strategy has been to speak more bluntly than most presidents have spoken about the economic risks -- to the point where Mr. Bush has been accused of talking down the economy -- but also to assert that policy proposals developed and debated during a period of confidence and optimism remain the right prescriptions for an era of uncertainty.
"But the purpose of these songs is pretty limited, usually to mate and also to assert territory… So each song doesn't have a particular meaning".
It is also, implicitly, to assert physical and sexual power.
Zanco is also quick to assert ownership of photographic rights.
The group may have also wanted to assert itself after the Shalit deal.
Chinese authorities have also sought to assert control by directly warning some online services.
But it has also continued to assert its faith in a policy of free trade.
The Pentagon is also moving to assert a more active role in human spying operations.
"They are also trying to assert the fact that this is the next generation of Islamic State recruits," he told The Independent.
