Nick of Time by Ted Bell

"Hard a'lee, me boys!" shouted Nick McIver over the wind, "or be smashed to smithereens in the jaws of Gravestone Rock!"

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Abstract: With the help of Lord Hawke, whose children have been taken by the evil pirate Captain Billy Blood, young Nick McIver uses a time machine to rescue the two children as well as change the course of events in two time periods, the Napoleonic Wars and World War II.

Publisher: St. Martin's/Griffin; 419 pages