Churchill, Brown & Manson Co. was active in trading primarily with Cuba. The main office was in Portland, Maine, but in 1867 an active branch office was started in Boston, Massachusetts. The company did extensive business in Cardenas, Cienfuegos, Havana, Matazas, Sagua La Grande and other Cuban ports, as well as some Puerto Rican ports, in the importing of sugar and molasses into the United States, and in exporting lumber, shooks, hogsheads, hoops, boxes, barrel staves and food stuffs to agents and dealers in the Caribbean.

James M. Churchill was the senior partner of the firm and apparently the dominant member of the company. (Mr. Brown is never mentioned, but one letter from an underling in Boston to his counterpart in Portland speaks disparagingly of Mr. Manson's competence.) Letters from Cuban agents to the main office in Portland mention Mr. Churchill's visit to the island in January and February 1871 with friendly warmth so that it is entirely possible that he was the J. M. Churchill who was the agent in Cardenas in 1863 and who made out the bills to be paid by E. P. Treat & Co. of Frankfort, Maine (Coll. 30). (Treat managed a barque JAMES M. CHURCHILL in 1867.) The firm not only dealt in the export of the materials in which sugar and molasses were to be imported, but it also contracted for shooks, staves, etc., from individual manufacturers on a yearly basis, storing such material until needed for export. It also dealt with midwest firms in buying flour for resale in St. John, New Brunswick, along the coast of Maine, along with other foodstuff, in Cuba. It would appear that weekly or biweekly advices were sent to a dozen or more sugar and molasses dealers and agents in Cuba as to the prices their products were bring in the Boston, New York and Portland markets. In turn, those dealers and agents sent quotations about the price and sales of sugar and molasses in Cuban ports and the prices that wooden containers were fetching in the local markets.

The letters give a good picture of the seasonal fluctuation of the sugar and molasses business in Cuba at that time from the harvesting of the cane in late November-December, the processing of the cane syrup in various forms, (muscovado, clayed sugar and molasses, treacle, "melado," "centrifugal," "refined," "grocery," etc.), the packing of the product destined for export into barrels and boxes ready for shipping and the ending of the season in April or May of the following year. Natural disasters - the drought and resulting fires of the sugar estates in March 1867, and the two serious hurricanes of October 1870 - affected the price, quantity and quality of the produce. This was also a time of unrest and rebellion against the Spanish government in Cuba. In November 1869 two or three estates had been burned and field hands carried off in the Cienfuegos district, while a "partial slave conspiracy" had been discovered and put down in Sagua La Grande and armed men had to protect each estate. Most of the vessels mentioned in the letters, invoices and bills of lading were American schooners, brigs and barques. Churchill, Brown & Manson Co. did not appear to have owned or acted as agents for the majority of these vessels, although most of them were from Maine ports. The firm seems to have maintained storage warehouses for both the imorts and exports as well as acting as agents in their sale.