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CLASSROOM ACTIVITY

Reading a battle through its numbers

Compare casualty figures across three battles of one war and argue what the uncertainty itself tells us.

Grade band
High school / undergraduate survey
Duration
45–60 minutes
Materials
  • One computer or a projector with internet access
  • The three battle pages on The War Atlas (linked below)
  • This handout, printed (one per student or group)
  • Optional: the battle_casualties.csv download from the open dataset

Free to print & photocopy for classroom use · CC BY 4.0

Every battle page on the atlas reports force strengths and casualties not as single hard facts but as figures graded by confidence, and as a range whenever the sources disagree. That honesty is the point of this activity. Students look at three battles of the American Civil War — Antietam (1862), Fredericksburg (1862), and Gettysburg (1863) — and argue what the numbers, and the uncertainty around them, actually tell us.

The goal is not to memorize casualty totals. It is to read a number the way a historian does: asking where it came from, how sure anyone is of it, and why one army’s losses might be known to the single digit while the other’s are only known to within several thousand.

Steps

  1. Open the three battle pages — Antietam (1862), Fredericksburg (1862), and Gettysburg (1863). For each battle, find the casualty figures for both sides and copy them into a table on your handout, along with the confidence grade shown next to each.
  2. Circle every figure that is written as a range(two numbers) rather than a single number. You will find that most are single numbers — but Gettysburg’s Confederate casualties are given as a band of several thousand. Why would one army’s losses be reported so much more precisely than the other’s?
  3. Notice that everyfigure — even the precise-looking ones like Fredericksburg’s 12,653 Union casualties — carries a “medium” confidencegrade. Discuss as a group: what does “medium confidence” mean for a number written down to the last digit?
  4. Write a short claim (3–4 sentences) completing this sentence: “The casualty numbers for these battles are best understood as ___ because ___.” Support it with at least one specific figure from your table.
  5. Extension: download battle_casualties.csv from the open dataset, filter it to these three battles, and sort by the high-casualty column. Does your ranking match what the pages show? What does the CSV give you that the pages don’t?

Discussion questions

  • If two textbooks give different casualty totals for the same battle, does that mean one of them is wrong? What else could explain the difference?
  • Why might a careful historian choose to publish a range (say, 23,000–28,000) instead of picking one number and stating it plainly?
  • A figure like “12,653” looks more authoritative than “about 12,000–13,000.” Which is the more honest way to report an estimate, and why?
  • What kind of records does an army need to keep for its casualty count to be trustworthy? What happens to those records during a retreat?

Teacher notes

The feature this exercises:the atlas grades every force and casualty figure by confidence and shows a range when sources disagree, rather than flattening everything to one clean number. All three battles here are graded “medium” confidence; the teachable contrast is between the precise-looking single figures and Gettysburg’s honestly-ranged Confederate total, all carrying the same modest confidence.

Background you don’t need to pre-teach: Union casualty reporting was systematic; Confederate figures — especially after the retreat from Gettysburg — rest on incomplete returns, which is why that number is published as a band. Let students infer this from the data and surface it in discussion rather than front-loading it.

What “right” looks like: this is a sourcing-and-evidence exercise, not a memorization drill. A strong answer is a well-reasoned argument about uncertainty, not a single correct total. Because the catalogue is periodically revised, have students record the date they accessed each page.

Grade-band note: written for high-school and undergraduate survey courses. For middle school, drop the CSV extension and run steps 1–4 as a whole-class activity.