By the advice of various powerful friends in France, Grotius determined to make Paris his city of refuge. He was well received in the French metropolis, both by learned men and politicians, and in the beginning of the following year was presented to the King, who bestowed upon him a pension of 3000 livres. In the year 1622 he published his ‘Apology,’ in which he vindicates his conduct from the particular charges which had formed the subject of the proceedings against him, and argues against the legality of his sentence and the competency of the tribunal by which he was tried. His work excited much attention throughout Europe, and greatly irritated the States-General, who published so violent an edict against it, that the friends of Grotius entertained fears for his personal safety. In order, therefore, to place himself more fully under the protection of the French government, he obtained letters of naturalization from Louis XIII. In 1625 he completed his treatise ‘De Jure Belli et Pacis,’ which was published at Paris in that year. None of the works of Grotius have excited so much attention as this treatise: it was the first attempt to reduce into a system the subject of international law; and the industry and extensive learning of the author well qualified him for the task. More complete and useful works upon this subject have been written since the time of Grotius; but in order to estimate properly the magnitude and value of his labours, it should be considered that, before he wrote, the ground was wholly unbroken. In his own age, and in that which succeeded it, this work was held in the highest estimation, being translated into various languages, and circulated as a standard book throughout Europe. Grotius remained more than nine years in France, and during that period published, in addition to the works already noticed, several theological treatises of small interest at the present day. The latter part of his residence in France was rendered uncomfortable by several disagreeable circumstances, and in particular by the backwardness of the French government in paying his pension. He made various attempts to return to Holland, which were discouraged by his friends, as the sentence against him was still in force; but towards the latter end of the year 1631, finding his abode in France intolerable, he determined at all hazards to revisit his native country. He soon found, however, that he had taken an unwise step: the States-General issued an order for his arrest, and after in vain endeavouring to appease his enemies, he quitted Holland in March 1632, intending to take up his abode at Hamburgh, which place he did not, however, reach before the end of the year.