There was never a time in English history when the possession of an
ancient name and wide estates gave greater opportunities for taking
a large share in public affairs than when the fifth Earl attained
his majority. It was natural, therefore, that a young man who was
recognised by his friends as above the average should be regarded as
a person of unusual political promise.

In 1775 an offer was made to him of the sinecure post of Lord of the
Bedchamber. He declined it, on the openly declared ground that the
position of an official at Court was such as "damps all views of
ambition which might arise from that quarter." But in 1778 there
came an opportunity of satisfying his public spirit and ambition by
crossing the Atlantic as a peace commissioner to America.

It is a curious historical fact that this mission appears to have
been partially, if not entirely, originated by Carlisle himself. The
story of its inception and the outlines of its progress are told by
Carlisle in a letter preserved at Castle Howard, which he addressed
to his friend and former tutor, Mr. Ekins. It is doubtful if the
King ever really hoped or intended that Carlisle's mission should
have a successful issue. It ended, as history has told, in absolute
failure. Carlisle returned home with the barren honour of good
intentions.

The trying work which he had undertaken entitled Carlisle, however,
to posts of importance at home, and he subsequently filled the high
office of Lord-Lieutenant of Ireland, under the administration of
Lord North. When on the resignation of Lord Shelburne, in the year
1783 the memorable and short-lived coalition between Fox and North
was formed, Carlisle became one of the Cabinet as Lord Privy Seal.