This is the beginning of Part 1: Monday, June 29, 1863.
A Confederate spy crawls on his belly over some rocks, before looking out and discovering that he can see the whole Union army, which is stretching like a gigantic snake as it marches out of a rainstorm.
The spy estimates the Union army's numbers. He notes that the part of the army he's looking at is under the command of Union General Reynolds and that these dudes are moving fast.
The spy sneaks away as it starts to get dark and rides off to find the Confederate Headquarters near Chambersburg. His horse is tired, and he worries about accidentally getting shot by his own comrades after nightfall, as he rides into the line.
The spy quotes Shakespeare from memory as he rides. He's an actor and is finally getting some parts thanks to the fact that the war has been dragging others away. He wishes that the Confederate leadership could see what a good spy this makes him.
The spy spots the tracks of cavalry. He follows the tracks and questions a local farmer, pretending to be a farmer himself, looking for a runaway wife. The farmer tells him the tracks belong to Yankee cavalry.
The spy heads off to reach the headquarters of Generals Lee and Longstreet. They're the Confederate commanders, and they're an odd match.
The spy stops and eats a little dinner before riding onwards, with Shakespeare still drifting through his head. Finally, he runs into the Confederate picket line.
Fortunately, the sergeant who intercepts the spy agrees to lead him to Longstreet. One of the soldiers tells the spy that they'll have to hang him if he doesn't actually know anybody at headquarters—which, naturally, freaks the guy out a little.
Longstreet lies in his tent, watching the rain and thinking about his dead children. His aide, Sorrel, arrives, and tells him that the spy—named Harrison—has just arrived.
Longstreet recalls his first meeting with Harrison and gets dressed.
Sitting on his horse, Harrison is totally soaked. He dismounts and talks to Longstreet, as Sorrel brings them coffee and cigars. Harrison points out the he came through the picket line in the dark—which is a pretty dangerous thing to do.
Harrison gives Longstreet the position of the Union army and estimates the total number of soldiers on the move under the leadership of General John Reynolds. This info surprises Longstreet, but he doesn't show it.
Harrison guesses that Longstreet had no idea about any of this, saying that Longstreet wouldn't have spread the army out so far if he'd known. Longstreet realizes the Union probably knows how spread out they are now.
Longstreet suggests that J.E.B. Stuart, a Confederate cavalry commander, would have said something about these developments if they were true, but Harrison says that Stuart doesn't seem to be accomplishing much. Harrison also notes that he saw tracks from a column of Union cavalry a little while ago, probably General Buford's.
Longstreet instinctively knows that Harrison is right and that Stuart has just been joyriding.
He and Harrison head out to meet General Lee.
Longstreet worries that Lee will be skeptical—the Old Man doesn't trust spies, but he loves General Stuart.
Longstreet never thought invading the North was a good thing. He wanted to fight more defensively, but Lee and Jefferson Davis overruled him
Harrison talks about how the Confederates seem much more cheerful and ready to fight than the desperate and tired Yankees. He then remembers to tell Longstreet that the head of the Army of the Potomac (the Union army in the East, where they are) has changed: it's now General Meade, not General Hooker.
Harrison brags about his disguise: he's been going around as a farmer searching for his wife, who ran away with a drummer. It turns out that no one seems to care much about the farmer's plight.
Longstreet and Harrison reach Lee's camp. Lee's aide argues about waking Lee up, but the guys insist.
Lee stands in the tent, looking old and noble.
The over-excited Harrison bows to Lee with a flourish.
Looking at the map, Longstreet fills Lee in on the Union position, as Harrison provides some details.
Lee thanks Harrison for his aide and courage in approaching the picket line. Harrison leaves, thanking Lee.
Lee is reluctant to move on a spy's word and without info from Stuart, but Longstreet says they don't have a choice. Lee is surprised the Union picked Meade instead of Reynolds to lead.
Longstreet advises swinging the army around and cutting the Yankees off from Washington.
Lee wants to move the army. He decides to send it towards the town of Gettysburg, starting at first light.
Longstreet is glad about this and says he's sorry for waking Lee up so late. The men stand in silence, and Lee says that he'll miss these conferences with Longstreet once the war is over.
Longstreet rides back to his tent, thinking about the soldiers sleeping around him and about the battle they'll be headed toward.