When the King asks little Prince Paul about his first day of school, Paul says, ``I had to write a letter.'' Pleased, the King tells the Queen, surmising that the letter must have been to Paul's pal Prince Peter, across the valley. The Queen passes the word to the Queen Mother, who's overheard by the maid, who tells the cook, and so on, each adding and embellishing until, by evening, the exaggerated story has caused the kingdom to muster in full military array against Prince Peter's friendly domain. Fortunately, this threat is dispelled next morning before the first shot, when Paul finally mentions that the ``letter'' was ``a''—``and today I am going to...write...``b.'' The familiar scenario is developed with logic and a brisk good humor; Goffe's well-designed illustrations and broad caricatures make an entertaining complement. (Picture book. 4-8)