 Well certainly there is a move which seems to require some explanation: the move from truth to necessity. Why should it follow from the fact that it was true in 1900 that a sea-battle would take place on 1/1/2100, that it was necessary that it should? This looks, indeed, suspiciously like a fallacious move from “Of necessity, if it is true that a sea-battle takes place on 1/1/2100, a sea-battle takes place on 1/1/2100” to “If it is true that a sea-battle takes place on 1/1/2100, a sea-battle takes place of necessity on 1/1/2100”. But such suspicions are probably ill-founded. It is more likely that the move invokes a certain form of the correspondence theory of truth: if what someone says at a certain time is true, then the state of the world at that time must be such as to make it true. But since what is, necessarily is when it is, the state of the world will be necessary. So, anything that is true is necessarily true.