ral[771], October 13, 1639, in which he puts him in mind that it was
his Excellency's brother first proposed to him his entering into the
Swedish service: he afterwards makes an offer of his son, who had served
two years under Boschius, chief Engineer to the Prince of Orange, and
had since been several years one of the Duke of Weymar's Pages. After
the death of that illustrious Prince, who shared with Bannier the glory
of being the greatest general in Europe, he thinks he cannot do better
than give him to Marshal Bannier, who was unanimously allowed to hold
the first rank in the art of war. He begs that his son may be only
employed in things of which he is capable. On the same day he wrote to
Salvius, desiring him to recommend Diederic to the Marshal.

Whilst Grotius was thus employed in placing his son, Diederic
entertained a design of entering into the Dutch service. His father was
highly displeased with this project; and wrote to him, and to William
Grotius, that it was most improper for him to expose his life for his
cruellest enemies; and that Sweden was his true country, and to that
kingdom he ought to devote his life, and from it to merit and expect
honours. "If my son dislikes the activity of a military life, Grotius
writes to his brother, he may find ease, and acquire honour in General
Bannier's houshold, or by exercising his profession of Engineer. I shall
always give him my assistance, and I hope I have as many friends
elsewhere, as I have enemies in Holland. If my son disgraces himself so
far, as to ask favours from the Dutch, he is unworthy to call me father.
If he chuses rather to be an Ensign with you, than a Captain among
others, he is mean-spirited, and forgetful of what he has been."
Diederic had a design of writing the history of the Duke of Weymar;
which project Grotius approved of, as worthy of a grateful mind. He sent
him word, that if he would set about this work whilst he was with
Marshal Bannier, he would make his court by it to that General, who had
it in his power to reward him. Diederic at last complied with his
father's desire, and went to Marshal Bannier's camp. He was made a
prisoner of war by the Bavarians in an unfortunate action near Dillingue
and Memingue, in the end of the year 1643. Grotius immediately set all
his friends to work to procure his son's liberty: he wrote to the famous
John de Vert, and applied to the Duke of Bavaria that he would be
pleased to send him back as soon as po