1400- the year the Emperor visited England to seek the help of the King

Only defeat of the Turks by the Mongol Chief Timur at the Battle of Angora in 1402 prevented an earlier showdown in Constantinople, prior to her eventual fall in 1453. In 1399, the Emperor, Manuel II. Palseologus was so desperate that he set out on a European tour to seek help. Having first visited Paris, he landed in Britain on 11 December, as is recorded in the Chronicle of Adam of Usk- 

The emperor of the Greeks, seeking to get aid against the Saracens, visited the king of England in London, on the day of Saint Thomas the Apostle (21st December), being well received by him, and abiding with him, at very great cost, for two months, being also comforted at his departure with very great gifts. This emperor always walked with his men, dressed alike and in one colour, namely white, in long robes cut like tabards ; he finding fault with the many fashions and distinctions in dress of the English , wherein he said that fickleness and changeable temper was betokened. No razor touched head or beard of his chaplains. These Greeks were most devout in their church services, which were joined in as well by soldiers as by priests, for they chanted them without distinction in their native tongue. I thought within myself, what a grievous thing it was that this great Christian prince from the farther east should perforce be driven by unbelievers to visit the distant islands of the west, to seek aid against them. My God! What dost thou, ancient glory of Rome? Shorn is the greatness of thine empire this day ; and truly may the words of Jeremy be spoken unto thee: "Princess among the provinces, how is she become tributary " (2 Lament, i. 1.) Who would ever believe that thou shouldst sink to such, depth of misery, that, although once seated on the throne of majesty thou didst lord it over all the world, now thou hast no power to bring succour to the Christian faith? 

The king kept Christmas with the emperor at Eltham.