In the fall of 1805, in October of which year he was made a full colonel, Colonel Brock returned to Europe on leave; and early in the following year, he laid before his royal highness the commander-in-chief the outlines of a plan for the formation of a veteran battalion, to serve in the Canadas.  In support of the plan he wrote: 

“The advantages which may attend the establishment of a corps such as is here recommended, will be perhaps more clearly understood by first adverting to some of the causes that produce the inconvenience to which the troops occupying the frontier posts of that country are continually exposed.

“A regiment quartered in Upper Canada is generally divided into eight different parts, several hundred miles asunder, and in this situation it remains at least three years.  Great as is the evil incidental to a state of separation, even where the mind is in no danger of being debauched, what may not be apprehended in a country where both the divided state of the regiment, and the artifices employed to wean the soldier from his duty, conspire to render almost ineffectual every effort of the officers to maintain the usual degree of order and discipline.  The lures to desertion continually thrown out by the Americans, and the facility with which it can be accomplished, exacting a more than ordinary precaution on the part of the officers, insensibly produce mistrust between them and the men, highly prejudicial to the service.

“Experience has taught me that no regular regiment, however high its claim to discipline, can occupy the frontier posts of Lower and Upper Canada without suffering materially in its numbers.  It might have been otherwise some years ago; but now that the country, particularly the opposite shore, is chiefly inhabited by the vilest characters, who have an interest in debauching the soldier from his duty; since roads are opened into the interior of the States, which facilitate desertion, it is impossible to avoid the contagion.  A total change must be effected in the minds and views of those who may hereafter be sent on this duty, before the evil can be surmounted.”

In a letter from Lieut.-Colonel Gordon, dated Horse Guards, January 17, 1806, Colonel Brock received the Duke of York’s “thanks for the communication of his very sensible observations respecting the distribution of the troops in Canada, which his royal highness will not fail to take into consideration at a seasonable opportunity."[19]

While on a visit to his family and friends in Guernsey, Colonel Brock deemed the intelligence from the United States to be of so warlike a character, that he resolved on returning to Canada before his leave was expired; and such was his anxiety to be at his post, that he overtook at Cork the Lady Saumarez, a Guernsey vessel, well manned and armed as a letter of marque, bound to Quebec.  He left London on the 26th June, 1806, and hurried away from Europe never to return—­never to revisit those who fondly loved him, not only from ties of kindred, but for his many endearing qualities; but he had the satisfaction of knowing that the commander-in-chief was much pleased with the zeal and devotion evinced by him on this occasion.