alternatehistory.com

15 May
A Confederate attempt to cross the Mississippi at New Madrid is turned back with heavy casualties - several hundred lost. The aim had been to decoy the Eads Boats upriver and then gain a point with which to launch a raid, but the local defenders use their few cannon effectively to sink the assault boats as they cross.

16 May
Pennefather's troops reach the outskirts of Grand Rapids. His cavalry get into a skirmish, and he orders the army to close up and deploy - planning to attack the Union positions the following day.

17 May
Austin Blair is dug in on the Grand River and the Rogue River with around 20,000 troops, and plans to defend tenaciously - he knows the British supply line has to be under some strain, as his men tore up the rail line from Detroit to Grand Rapids where practical, and he believes that his 20,000 reinforcements from Missouri are en route (in actuality the number is nearer 10,000 than 20,000 given diversions to the Kentucky problem). As such he hopes to hit Pennefather from behind with the reinforcements.

For his part, Pennefather elects to begin with a long-range cannonade, making use of counter battery with his 12-lbers while bringing up his 40-lber siege train. Few Union guns are identified (perhaps partly because not a great deal are present) but any which make the mistake of firing and hence giving away their position are subjected to a counter-battery shoot at a range of considerably more than a mile.

Blair's reinforcements detrain over the course of the day at Ann Arbor, and begin a march for Detroit. They are spotted at 7 in the evening by a Canadian militia cavalry unit, which races to inform the new Detroit garrison.