War with the Newts

On the distant island of Tana Masa, Captain van Toch discovered animals unknown to science—giant salamanders. The lonely captain came to love the clever little creatures as if they were his own children. Van Toch teaches the salamanders to use human tools. He brings them harpoons and knives, receiving pearls in return.
Returning to his homeland, the Czech lands, van Toch meets his childhood friend—the billionaire Mr. G.H. Bondy.
Together they create the powerful Salamander Syndicate, which trades the animals as cheap labor for underwater construction. The salamanders learn to speak and turn out to be intelligent beings, though their intellect should not be overestimated, as it is no higher than that of the average human.
The global economy can no longer exist without cheap salamander labor. But the world powers use salamanders not only for peaceful construction. They arm these creatures so that the salamanders will defend their national interests across the seas and oceans.
However, people miscalculated. The salamanders start a war against them, flooding countries and continents, conquering living space for themselves. Humanity is unable to unite against the common deadly enemy. Human civilization is doomed to destruction.