Geologically, the Rock River is older than Lake Michigan. Before the glaciers came to Illinois, the Rock River linked up with the Illinois River east of Princeton. Glaciers buried that section that linked the two great rivers with loose rock, however, water still flows in that underground river today. It is now called the Princeton Aquifer.
The area between the Mississippi River and the Fox River (west of Chicago) was once the hunting grounds of the Illinois Indians after they migrated here from the Pacific coast around A.D. 900. Later, as the Illinois began to decline due to wars with the Sauk, Fox, Iroquois, and Sioux and illnesses introduced by contact with the French, the land was settled by the refugee tribes of the Sauk (or Sac) and Fox Indians fleeing the Iroquois Raids to the East and the French to the north (Green Bay Area).
In 1804 the Sauk and Fox tribes first signed a treaty with the U.S. Government in St Louis relinquishing all their holdings east of the Mississippi. At that time the tribes lived primarily across the river in the area now known as Iowa.
In the War of 1812, a tribal leader named Mucata Muhicatah (English translation is Black Sparrowhawk which was shortened to Blackhawk) fought for the British and was with Tecumseh when Tecumseh was killed near Detroit.
In spring 1831, Blackhawk lead a rogue Sauk group across the Mississippi to resettle their homeland. General Gaines lead a 1500 man force against them and when Blackhawk heard of the approaching force, he crossed again to the west bank of the Mississippi and signed a treaty while General Gaines's forces torched the Indian village at he and his followers left behind.
In spring 1832, Blackhawk once again crossed the river, however this time with an estimated 700 warriors and many women and children. Governor Reynolds of Illinois called up the Illinois Militia again and over 1800 men gathered in the area of John Dixon's home on the Rock River.
On May 12th, a detachment of 275 men lead by Major Stillman left Dixon and marched north along the banks of the river without orders to do so allegedly seeking the glory that would come to them by defeating the Indian leader. As they marched they eventually abandoned their supply wagons and continued to march northward hoping to be fast enough to catch Blackhawk's group. At Old Man Creek in the area now known as Stillman Valley (however after the incident known as Stillman's Run), some of Stillman's forces decided to make camp for the night, however another group of Major Stillman's forces still pressed on and caught up to a small group of Sauks. The fact that they caught the Sauks is almost admirable (except that they were not supposed to have left Dixon), however the end result would be the worst defeat any United States military force would suffer at the hands of Native Americans (until Little Bighorn). Two small groups engaged each other when suddenly a larger force of about 40 Sauks attacked, swooping in quickly, and yelling and hollering creating the sound of a much larger force. The green Illinois Militia troops were terrified and attempted to flee back to Major Stillman's camp, but the soldiers in camp, without supply wagons, sentries or warnings of a impending battle were helpless. The Sauks drove the Illinois Militia back thru Major Stillman's camp and chased them all over the prairie that night. After Stillman's Run; that Illinois Militia would never recover. On May 27th, the Dixon Militia was discharged from service by the Governor of Illinois, who had determined they were too demoralized and undisciplined to be able to successfully carry out an Indian campaign.
Just east of Byron Illinois is Stillman Valley, and in the town playground, just off Illinois Route 72, you'll find a historical marker indicating that spot as where Stillman was camped and routed. Along the Rock River just south of Byron, you'll see a large statue of Blackhawk, looking downstream.
Governor Reynolds again set out to raise an army. Meantime; the Sauk attacked the Apple River Fort and were repulsed by its defenders in a 15 hour battle. Then Wisconsin Militia's General Dodge (who would later become Governor of Wisconsin) repulsed the Sauks at Fort Hamilton on the Pecatonia River near present day Rockford.
General Scott had been ordered to take his army from Fort Monroe on Cheseapeake Bay to Illinois. They marched 18 days to Chicago but before arriving suffered a major cholera breakout that would haunt them for the rest of the war. When Scott arrived in Chicago's Fort Dearborn, cholera would break out in Chicago. Scott's forces rested in Chicago for a month before blazing a trail into the prairie. That trail still exists today and is called Army Trail Road and runs thru the western suburbs. Scott's army continued to bury cholera victims along the route and buried several in the vicinity of Salt Creek. With Scott's army moving slowly because of the cholera, a new Illinois Militia would fight again with the still moving Sauk tribe. In the Battle of the Wisconsin, Illinois and Wisconsin Militias under Generals Dodge, Alexander and Henry would inflict much more damage on Blackhawk's forces.
The final battle of the Blackhawk War would be in Wisconsin at the Bad Axe River. Here, U.S. Regulars under General Atkinson, Wisconsin and Illinois Militia forces under Generals Dodge, Alexander and Henry, as well as Winnebago and Sioux tribes would destroy the majority of Blackhawk's forces. Blackhawk, Naapope (Blackhawk's son) and Wabokishick (referred to as Prophet, and no, he wasn't the same prophet who advised Tecumseh at the much earlier Battle of Tippecanoe) would escape along with about 20 warriors to the "Dalles on the Wisconsin" (the area referred to today as the Wisconsin Dells). Winnebago and Sioux warriors took pursuit and returned the three to General Street per a pre-arranged deal. The final treaty was to be signed in Rock Island, however, General Scott had arrived with his army, bringing cholera with them, so General Street retreated with his prisoners to Jefferson's Barracks near St Louis.
Blackhawk, Naapope, and Wabokishick were held prisoners (hostages) in Washington D.C. to ensure that the Sauk Tribe would not cross the Mississippi again. They were released from prison June 4th, 1833 and paraded on the eastern coast before being allowed to return home to Iowa. Blackhawk would die on October, 3rd, 1840 and was buried on the banks of the Mississippi.