Chamberlain was a real Colonel of the 20th Maine. His defense of Little Round Top, including the bayonet charge, is historically accurate, though the film (and book) significantly elevates its overall importance in the battle compared to some academic histories.

Lee's command and key decisions are depicted. However, the portrayal by Martin Sheen is criticized by some historians for being physically dissimilar and perhaps too subdued or contemplative compared to accounts of Lee's presence and occasional temper.

Longstreet's role as Lee's second-in-command and his advocacy for defensive tactics are accurate. His documented disagreements with Lee over strategy at Gettysburg, particularly regarding the attacks on Day 2 and Pickett's Charge, are central to the film and historically based.

Buford's crucial role in recognizing the strategic importance of Gettysburg and deploying his cavalry to delay the Confederate advance on July 1st is accurately portrayed. Sam Elliott's portrayal is often praised.

Pickett was a real general whose division spearheaded the famous charge. The film captures his flamboyant personality, but some dialogue attributed to him is from the novel.

Armistead was a real Confederate brigadier who was mortally wounded during Pickett's Charge near the Union lines. His pre-war friendship with Union General Hancock is historical, though the emotional depth and specific dialogue regarding it are dramatized in the novel/film.

The film accurately depicts Brig. Gen. John Buford's crucial delaying action with dismounted cavalry against Confederate infantry west of Gettysburg on July 1st, buying time for the Union army to consolidate.

The death of Maj. Gen. John F. Reynolds early on July 1st while positioning troops is a key historical event accurately shown.

The 20th Maine's desperate defense of the Union left flank on Little Round Top, culminating in a bayonet charge when out of ammunition, occurred as depicted and was a significant engagement on Day 2.

While the fight for Little Round Top was important, the film (following the novel) arguably overemphasizes its singular importance compared to other critical Day 2 actions, such as the fighting at Culp's Hill, the Wheatfield, or Devil's Den, which receive less/no focus.

The strategic disagreements between Lee and Longstreet, particularly Longstreet's preference for defensive maneuvers and his strong objections to the frontal assault on Day 3 (Pickett's Charge), are well-documented historically.

The scale, formation, devastating artillery fire, and ultimate failure of the massive Confederate assault on the Union center on July 3rd are depicted with considerable accuracy regarding troop movements and outcome, though battlefield chaos is inherently simplified.

Brig. Gen. Lewis Armistead did lead his men over the stone wall at the Union center (the "Angle") before being mortally wounded, representing the furthest point of the Confederate advance during Pickett's Charge.

Lee's meeting the retreating survivors of the charge and stating, "It is all my fault," is based on historical accounts.

The film largely omits the intense and prolonged fighting for Culp's Hill on the Union right flank (Days 2 & 3), which was a major part of the battle involving significant forces and casualties.

Aside from Buford's initial stand, major cavalry engagements, such as the large battle east of Gettysburg on Day 3 involving Stuart and Gregg, are not depicted.

Many specific conversations, particularly intimate ones like those between Armistead and Longstreet or the exact wording of the Armistead/Hancock farewell, are dramatic inventions from the novel, not directly recorded history.

While showing battle, the film intentionally avoids graphic gore. Critics note it doesn't fully capture the horrific, bloody reality of Civil War combat casualties compared to historical descriptions.

Unprecedented access was granted by the National Park Service, allowing significant portions of the film, including Pickett's Charge and Little Round Top scenes, to be filmed on the actual historical locations.

Thousands of volunteer Civil War reenactors participated as extras, bringing a high level of authenticity to the appearance of soldiers, formations, and large-scale movements, contributing greatly to the film's realism.

Great care was taken, aided by reenactors and historical consultants, to ensure uniforms, flags, weaponry (muskets, cannons), and accoutrements were accurate for both Union and Confederate armies in mid-1863.

The film accurately portrays basic Civil War infantry tactics like firing in line, volley fire, and charges, as well as the use of artillery, largely thanks to the expertise of the participating reenactors.

Filming on location allowed for accurate representation of key terrain features like Little Round Top, Cemetery Ridge, Seminary Ridge, and the fields of Pickett's Charge, crucial to understanding the battle.

The film captures aspects of camp life, marching, the interactions between officers and enlisted men, and the general atmosphere of large armies maneuvering for battle.

Minor goofs exist, such as visible breath during July battle scenes (indicating cold filming conditions) or incorrect assumptions about moonlight based on historical lunar data for Meade's arrival scene.