In such a crowd of names, dates, and the like, there must be many small inaccuracies. In the case of the smaller dates, those which do not mark the great epochs of history, nothing is easier than to get wrong by a year or so. Sometimes there is an actual difference of statement in different authorities. Sometimes there is a difference in the reckoning of the year. For instance, In what year was Calais lost to England? We should say 1558. A writer at the time would say 1557. Then again there is no slip of either pen or press so easy as putting a wrong figure, and, except in the case of great and obvious dates, or again when the mistake is very far wrong indeed, there is no slip of pen or press so likely to be passed by in revision. And again there is often room for question as to the date which should be marked. In recording a transfer of territory from one power to another, what should be the date given? The actual military occupation and the formal diplomatic cession are often several years apart. Which of these dates should be chosen? I have found it hard to follow any fixed rule in such matters. Sometimes the military occupation seems the most important point, sometimes the diplomatic cession. I believe that in each case where a question of this sort might arise, I could give a reason for the date which has been chosen; but here there has been no room to enter into discussions. I can only say that I shall be deeply thankful to any one who will point out to me any mistakes or seeming mistakes in these or any other matters. The maps have been a matter of great difficulty. I somewhat regret that it has been found needful to bind them separately from the text, because this looks as if they made some pretensions to the character of an historical atlas. To this they lay no claim. They are meant simply to illustrate the text, and in no way enter into competition either with such an elaborate collection as that of Spruner-Menke, or even with collections much less elaborate than that. Those maps are meant to be companions in studying the history of the several periods. Mine do not pretend to do more than to illustrate changes of boundary in a general way. It was found, as the work went on, that it was better on the whole to increase the number of maps, even at the expense of making each map smaller. There are disadvantages both ways. In the maps of South-Eastern Europe, for instance, it was found impossible to show the small states which arose in Greece after the Latin conquest at all clearly. But this evil seemed to be counterbalanced by giving as many pictures as might be of the shifting frontier of the Eastern Empire towards the Bulgarian, the Frank, and the Ottoman.