A year after his return to the east Parkman published an account of his adventures in the Knickerbocker Magazine, under the title The Oregon Trail, the name by which the old route was generally known. Later on these sketches appeared in book form. They formed Parkman's first book and indicated the scheme of his life-work.

Parkman had elaborated his first idea, and now intended writing an account of the history of the French influence in America from the earliest visits of Verazzani and Jacques Cartier, down to the time when the English drove out the French from Canada and the Mississippi Valley, and laid the foundations of what was destined to be the American Republic.

His second book, The Conspiracy of Pontiac, published five years after his adventures among the Sioux, deals with the last act of the struggle between France and England. This book appeared thus early in the series because at that time, on account of ill-health, Parkman could not begin any work of vast magnitude such as would require exhaustive research.

The conspiracy of Pontiac, a chief of the Ottawas, who formed a confederation of the tribes to drive the English from the forts near the Great Lakes, was a theme complete in itself, and yet one that could easily supplement any series dealing with similar subjects. Parkman visited the scene of Pontiac's exploits, talked with the descendants of the tribes which still lingered around the Great Lakes, which then formed the outposts of the English, and stored his mind with such local traditions and color as would give character to the narrative. The book was written through the aid of readers and an amanuensis, whose task it was to gather the notes, which Parkman sifted until ready for dictation. It dealt with one of the most picturesque episodes of the French and Indian War, and the character of Pontiac—brave, patriotic, and ready for any fate—was drawn with a master-touch.

Fourteen years passed by before Parkman presented another volume of the series which he intended should illustrate the complete history of the French in America. This volume was called the Pioneers of France in the New World, and opens the theme with a description of the early voyagers, thus making it in point of place the first book of the series.

His books, which appeared at different times after the Pioneers of France, under the titles The Jesuits of North America; The Discovery of the Great West; The Old Regime in Canada; A Half Century of Conflict; and Montcalm and Wolfe, indicate each in turn the character of its scope.

They tell the history of the French race in America for over two hundred years, beginning with the old voyagers who sought in America a region of romance and mystery which should rival the fairy realms of the poets of the Middle Ages, and ending with the last efforts of the Indians to recover their land from the grasp of the hated English.

Through all this period the Indians had regarded the French as friends. Jesuit missionaries had penetrated the wilds of the Mississippi, and had brought to the tribes on its banks the message of peace and brotherly love. They spread the story of Christ from Carolina to the St. Lawrence, and from the Mississippi to the Atlantic. They lived the Indian life, dwelling in lodges, eating the Indian food, conforming as much as possible to the Indian habits, and retaining, in their geographical descriptions, the Indian names of the lakes and rivers, so dear to the savage heart.

They made, in the main, a peaceful conquest of the country, and they won the natives to such a degree that in the contest with the English which ensued the Indian remained throughout the firm friend and ally of the French. The English had thus two enemies to deal with instead of one, the military knowledge of the French being in every case strengthened by the subtle and savage modes of Indian warfare. This state of things kept the final issue doubtful, even though the English won victory after victory, for the taking of a fort and the slaughter or capture of the garrison might be followed at any time by a murderous night attack from the savage allies, who ignored the civilized methods of war and would never acknowledge defeat.