Peter Bollinger

Breaking the Code

The year is 1780. The British have taken control of New York City. But people are spying on the British and sharing their secrets with the Patriots. Can you learn a secret code in time to pass on an important message?

By Jess McKenna-Ratjen, Illustrated by Peter Bollinger

From the May/June 2026 Issue

Learning Objective: Students will decode secret messages and explain how they were used during the American Revolution.

Lexile: 790L; 580L

Key Focus Area: Algebraic Thinking,

Other Focus Areas: Engineering

Standards

What You Need to Know About the American Revolution

Watch a video about the birth of our nation.

The American Revolution is well underway. You’re living with your mother in a small home near New York City. For four years, the British army has kept your city under tight control. Soldiers in red coats patrol the streets and gather at taverns, discussing plans to win the war against the rebel Patriots.

Your mother works at one of these taverns. As long as you can remember, she’s told you stories of how exciting it will be for America to become its own country. Now she’s part of the heroic and dangerous effort to make that dream a reality.

Every night, your mother listens to the British soldiers as she serves them food and drinks. If she overhears anything useful, she passes the information on to a group of spies who work for George Washington himself. She uses several different codes to hide what she writes, replacing letters with numbers so that only someone who knows how to translate the codes can understand her messages.

Tonight you’re studying one of these coded messages. Your mother wants you to be able to read any that come for her while she’s working.

She’s told you that each number in the code represents a letter, starting with the letter M. So M = 1, N = 2, and so on. The code continues past the letter Z, until you end with L as 26.

Here’s what it looks like for the beginning of the alphabet:

The American Revolution has started. You’re living with your mother in a small home. It’s near New York City. The British army has controlled your city for four years. Soldiers in red coats walk the streets. They meet at taverns. There, they talk about plans to win the war against the rebel Patriots.

Your mother works at one of these taverns. She’s told you stories about America becoming its own country for as long as you can remember. Now she’s part of a daring effort. It aims to make that dream come true.

Your mother serves food and drinks to British soldiers every night. She listens to them talk. She may overhear something useful. She passes the information on to a group of spies. They work for George Washington himself. She writes messages using different codes. She replaces letters with numbers. Only someone who knows the codes can read her messages.

Tonight you’re studying one of these coded messages. Your mother is working. So she wants you to be able to read any messages that arrive.

She’s told you that each number in the code stands for a letter. This system starts with the letter M. So M = 1, N = 2, and so on. The code keeps going past the letter Z. It ends with L as 26.

Here’s what it looks like for the beginning of the alphabet:

A → 15
B → 16
C → 17

Your mother left you the word below to put into code. Time to practice your spy skills!

Your mother left you the word below to put into code. Time to use your spy skills!

ATTACK

How would you write this in your mother’s code? Hint: You may want to write out the letters of the alphabet and place their numbers next to them as a guide.

Knock, knock! There’s someone at the door. You open it, but no one is there. As you turn to head back inside, you hear a crinkle under your feet. You spot a small piece of paper on the floor with a list of numbers on it. Could this be a secret message?

Excited, you run to your desk. Using the code, you try to decipher what the message says. It reads:

Knock, knock! There’s someone at the door. You open it. But no one is there. You turn to head back inside. You hear a crinkle under your feet. You spot a small piece of paper on the floor. It has a list of numbers on it. Could this be a secret message?

Excited, you run to your desk. You try to decipher what the message says using the code. It reads:

11 22 3 19 15 8 7

What does it say?

It uses the same code that your mother taught you! Using what you learned from her, you successfully decode your first message.

You blow out your candle and rush to the tavern. Through the windows, you can see soldiers in red coats clinking their glasses together and laughing. You make your way to the back of the tavern and wait for your mother in the kitchen.

Soon she appears carrying a tray of empty glasses. You show her the secret message and tell her what it says.

It uses the same code your mother taught you! You use what you learned. And you’re able to decode your first message!

You blow out your candle. You rush to the tavern. You look through the windows. You can see soldiers in red coats. They’re clinking their glasses together and laughing. You make your way to the back of the tavern. There, you wait for your mother in the kitchen.

Soon she appears carrying a tray of empty glasses. You show her the secret message. You tell her what it says.

Your mother nods in approval. But your work isn’t done! She’s still serving the soldiers. You’ll have to write a coded reply for her. She tells you to leave it on your doorstep where you found the first one.

The message your mother wants you to code is this:

Your mother nods. You’ve done a good job. But your work isn’t over! She’s still serving the soldiers. You’ll have to write a coded reply for her. She tells you to leave it on your doorstep. That’s the same place where you found the first message.

The message your mother wants you to code is this:

JAMES ROBERTSON

You race home, relight your candle, and get to work. What code do you write?

You race home. You light your candle again. Time to get to work. What code do you write?

With your message safely in code, you place the paper on your doorstep. One hour later, you open the door to peek outside. The message is gone!

You communicated your first message to the Patriots on your own! Great spy work!

You’ve written your message safely in code. You place the paper on your doorstep. You open the door to peek outside one hour later. The message is gone!

You shared your first message to the Patriots on your own! Great spy work!

Tools of Spycraft

During the Revolutionary War, American spies passed secret messages about things like British battle plans and troop movements to help Patriot fighters. Here are some ways spies kept their secrets hidden from the British.

Codes and Invisible Ink

If the British were to find a secret message, American spies wanted to be sure it couldn’t be understood. As you’ve learned, some spies wrote in code. One famous code book contained 763 numbers that represented different words, people, and places.

Sometimes agents wrote messages in invisible ink made from substances such as lemon juice, vinegar, or milk. The reader would heat the letter to reveal the message.

Codes and Invisible Ink

Sometimes agents wrote messages in invisible ink made from substances such as lemon juice, vinegar, or milk. The reader would heat the letter to reveal the message.

Sending Signals

Spies used signals to pass along secrets, sometimes with ordinary items like clothing. Anna Strong, who lived in New York, did this with laundry hanging on a line. If she hung a black skirt, it meant an American spy was in town. She signaled where others should meet the spy by hanging a specific number of handkerchiefs on the line.

Sending Signals

Dead Drops

Spies stashed messages in hidden places called dead drops. Here’s one example. One Rhode Island farmer pretended to support the British army. But he secretly recorded their plans. He hid his notes in the crack of a rock, which he covered with a stone. Later, another spy collected the notes from the dead drop.

Dead Drops

Why might the Patriots have needed multiple ways to share secrets?

Tools of Spycraft

Codes and Invisible Ink

Sometimes agents wrote messages in invisible ink made from substances such as lemon juice, vinegar, or milk. The reader would heat the letter to reveal the message.

Codes and Invisible Ink

Sometimes agents wrote messages in invisible ink made from substances such as lemon juice, vinegar, or milk. The reader would heat the letter to reveal the message.