The Climax on Seminary Ridge wayside marker is one of five on the grounds of the Thompson House, known as Lee’s Headquarters, on the north side of Chambersburg Road (US 30) on Seminary Ridge. (39°50’05.7″N 77°14’41.8″W; map)
From the marker:
Lee’s Headquarters at Gettysburg
Climax on Seminary Ridge
“On every side the passion, rage and frenzy of fearless men or reckless boys devoted to slaughter or doomed to death! The same sun that a day before had been shining to cure the wheat-sheaves of the harvest of peace, now glared to pierce the gray pall of battle’s powder smoke or to bloat the corpses of battle’s victims.”
—Augustus Buell, “The Cannoneer” (1890)
During the heavy fighting late in the afternoon of July 1, 1863, Seminary Ridge became the final defensive position of the Union’s First Army Corps west of Gettysburg. Twenty-one cannons and thousands of battle-weary men crowned the heights with the aim of repelling Confederate forces ascending the ridge. The Union line was buckling to the left and right but the position near the Thompson house was holding.
The 143rd Pennsylvania Infantry was posted here along with three guns of Lt. James Stewart’s Battery B, 4th United States Artillery, blasting deadly volleys of iron into Gen. Alfred Scales’s North Carolina soldiers across the Chambersburg Pike. The Confederates pushed onward, however, unhinging the entire Union line from Seminary Ridge. The position here around the Thompson house was the very last to fall. Union soldiers sought refuge in the railroad cut to your right and rear. Once the fighting ended, dead and wounded soldiers were scattered around here. The widow Thompson and her neighbors cared for the wounded men of both sides, while the dead of both armies were buried near the places where they fell.
From the caption to the drawing on the bottom left:
This 1890 sketch shows the men of Stewart’s Battery firing across the Chambersburg Pike at Scales’ North Carolinians. The Thompson House is depicted at left. From augustus Buell, “The Cannoneer” (1890)
From the caption to the map:
The Union position on Seminary Ridge became untenable once Confederate Colonel Abner Perrin’s South Carolinians gained the flank and rear of the Federal position.