"declaration of loyalty" is correct and usable in written English.
Generally, you can use it when you want to express an allegiance to someone or something. For example, "The president gave a stirring declaration of loyalty to his country."
We know that his words are more than a pro-forma declaration of loyalty.
One way of reading Gass's title, then, is as his declaration of loyalty to the life of sentences.
In fact, it was a declaration of loyalty to the American people against that very power structure.
With a few tweaks by its lyricists, Alan and Marilyn Bergman, it became a fiercely proud declaration of loyalty by the boyfriend of a married man.
As celebrity endorsements to political parties go, Daniel Radcliffe's declaration of loyalty to the Liberal Democrats appeared, on first impressions at least, to be a useful one.
Opponents of the prime minister believed their case was strengthened when Jane Kennedy, a respected environment minister, resigned after refusing to make a declaration of loyalty.
The coup enraged Hitler, who declared: "even if Yugoslavia at first should give declarations of loyalty, she must be considered as a foe and therefore must be destroyed as quickly as possible".
Some of their statements yesterday were not exactly effusive in their declarations of loyalty.
They detect an echo of communist propaganda in their rulers' declarations of loyalty to a military ally, plus an unwillingness to give straight answers.
There was fist-pumping and toothpick-grinning, accusations of diving and declarations of loyalty, while in the background shady businessmen looked on with bulging pockets.
They read as public declarations of loyalty to an audience of one — the media-obsessed president, who was gratified to see the statements as aides kept him abreast.
