The tensions between the United States and Spain over the Louisiana Purchase were high in 1806 because Spain resented the fact that Napoleon had sold the Louisiana Territory to the United States, whom they considered a threat to Spanish held territory in America. Many Americans expected war to break out soon between the two countries and the Governor of Upper Louisiana, General James Wilkinson, needed information about the poorly defined borders of southwestern Louisiana Purchase territory to prepare for this eventuality.

Some historians believe that since Wilkinson, who was a major member of the Burr conspiracy, may have had an ulterior motive for wanting information about the area. Burr and Wilkinson were planning a coup to separate the western states and territories from the Union. They also wanted to invade and capture the Spanish held territories of today’s modern Southwestern United States and establish a combined empire of the Spanish territory and the western states. If this plan was to work, the conspirators needed more information about the area than they already had and they needed someone to carry out this mission without raising the suspicions of either the Spanish or American authorities.  

Zebulon M Pike, just returning from his failed expedition to find the source of the Mississippi River, expected to have a well deserved period of inactivity. But Wilkinson, having standing orders to engage in intelligence operations against Spain by using army officers disguised as traders if necessary, was to discover what the Spanish were doing along the poorly defined southwestern border of the Louisiana territory ordered Pike to carry out this intelligence mission without the knowledge or approval of either President Jefferson or the War Department. The article Zebulon Pike: Hard-Luck Explorer by Bob Moore states that…“while in that area, it would be necessary, wrote Wilkinson, to "move with great circumspect, to keep clear of any hunting or reconnoitering parties from that province and to prevent alarm or offense." Pike's real mission was that of a spy.” (1)

As a cover for this intelligence mission, Wilkinson gave Pike three minor missions to complete. These missions were:

• First:  provide an escort for fifty-one Osage Indians ransomed from the Pottawatomie tribe and a delegation of Pawnees, Osages, and Otos returning from a trip to see President Jefferson. 
• Second: Negotiate a peace between the Kansas and Osage tribes, and attempt to make contact with the Comanche people on the high plains.  
• Third: Explore the headwaters of the Arkansas River, then to proceed south, locate the source of the Red River, and descend it to the Mississippi. (2) 

The Pike expedition began on July 15, 1806.  Pike’s expeditionary party included 17 men from his failed Mississippi River expedition; two new volunteer soldiers; his second-in-command, Lt. James Biddle Wilkinson, son of the general; a volunteer physician, Dr. John H. Robinson; and Baronet Vasquez, an interpreter from St. Louis.
 
The party made their way west along the Missouri River to complete the first phase of Pike’s mission, returning the Osage Indians to their villages on the border of present day Kansas.  After staying with this group for a period, the expedition was lead by a group of Osage Indians to a Pawnee village on the Republican River near the border of the modern states of Kansas and Nebraska.  It was at this village that the famous flag incident happened.  The Indians also told Pike that a large force of the Spanish army, led by Don Francisco Malgares, had arrived at the Village a few weeks earlier looking for the Americans.  

How the Spanish had learned of Pike’s expedition is unknown, but some historians believe that General Wilkinson, a double agent for Spain, may have informed the Spanish about Pike’s expedition and its true mission.  Another theory is that since Wilkinson was also involved in the Burr conspiracy his plan was for the Spanish to capture Pike and his men, enabling Pike to carry out his spying mission.  With this information, the Burr conspirators could invade Texas, Spanish held territory. 

Upon learning of this information, Pike, his party and a group of Osage guides followed the Spanish expedition south into Kansas to the Great Bend of the Arkansas River, where the present town of Great Bend, Kansas is located sometime in October of 1806.  On 28 October 1806, the party split up.  Lt. Wilkinson, five members of the party and the rest of the Osage Indian guides went east on the Arkansas River to the Mississippi River and from there back to St. Louis. Pike and the rest of his men continued to follow the Spanish south and west by following the Arkansas River hoping to find its source, and find the Comanche Indians but he failed to find them. 

(Incidentally, Pike’s party was following the same path of the future Santa Fe Trail. As a consequence, the expedition also traced a future commerce route for the United States. William Bucknell, who first used a mule team to make the journey to Santa Fe where he traded with the newly independent Mexico, opened this trail in 1821.)  While following the Arkansas River west, the Pike expedition passed through the Great Plains. They passed by or near the future town sites of Dodge City, Cimarron, Ingalls, Pierceville, Garden City and other towns in Kansas. It was while in this area of the Great Plains that Pike’s description of the region as “vast sandy deserts” helped create the myth of “The Great American Desert”, which delayed settlement of the area until the early 1870s.
 
By 11 November 1806, the expedition had made it as far as the present western border of Kansas.  It was at this time that Pike made a decision to continue west into the present State of Colorado, despite the fact that the party was ill prepared for winter climates, where they sighted the mountain, later named in Pike’s honor, on November 15, 1806. On 23 November 1806, while the majority of Pike’s party rested from their arduous journey at the site of present day Pueblo, Colorado, Pike, two men from the party, and Dr. Robinson attempted to reach the mountain but failed to do so and returned to the base camp. 
 
Soon afterwards, the party continued to follow the Spanish trail through Colorado.  The party faced snowstorms, frostbite, cold, and other dangers until on 26 February 1807 the Spanish found Pike and his men. The Spanish escorted Pike and his men to Santa Fe.  Where after spending some time in Spanish territory, the Spanish returned Pike and his men to the United States. While Pike was with the Spanish, he was able to complete his mission by gathering the information that Wilkinson wanted. 

Some historians speculate that Pike wanted the Spanish to find the expedition so that he could complete his ultimate mission, gaining information of the Spanish military situation in the Spanish held territory of North America, particularly along the poorly defined southwestern border of the Louisiana territory.  Others say that the Spanish rescued this expedition because the party had become lost in the uncharted wilderness of the Rocky Mountains of Colorado.

Sources:
1) (Zebulon Pike: Hard-Luck Explorer by Bob Moore, Park Historian of the Jefferson National Expansion Memorial National Park, St. Louis, MO.)

2) Ibid.