The Confederate sympathizer who secretly saved Maryland’s greatest aqueduct in 1862

Thomas Walter’s Desperate Gambit to Save Monocacy Aqueduct

Thomas Walter had a tough choice in 1862. The lockkeeper at Lock 27 on the C&O Canal since 1839 was a known Confederate fan when General Hill’s troops crossed into Maryland.

Hill wanted to blow up the huge Monocacy Aqueduct – a 516-foot stone bridge with seven arches that let Union boats move troops and supplies. Walter had to pick sides fast.

He talked Hill into just draining the canal instead, getting so worked up that folks thought he might be locked up. His quick thinking saved the aqueduct while still looking loyal to the South.

The magnificent structure still stands today at C&O Canal National Historical Park, where you can walk across this engineering marvel that almost didn’t make it.

Thomas Walter Kept Lock 27 Running for 23 Years

Thomas Walter worked as the lockkeeper at Lock 27 (Spinks Ferry) on the C&O Canal since 1839. His neighbors knew him as a Confederate supporter, but he kept his job anyway.

Lock 27 sat at a key spot near the Point of Rocks crossing between Maryland and Virginia. The canal moved troops, bullets, and food for Union forces along the Maryland-Virginia border.

Walter knew the waterway inside and out after working there for over 20 years.

Confederate Troops Crossed the Potomac to Destroy the Canal

General D.H. Hill’s Confederate troops crossed the Potomac at Point of Rocks on September 4, 1862, during Lee’s Maryland Campaign. They planned to destroy the huge Monocacy Aqueduct to stop Union boats on the canal.

The aqueduct stretched 516 feet with seven stone arches, making it the biggest structure on the entire C&O Canal. Hill’s men spent that night and the next day breaking canal banks and smaller locks.

An Amazing Structure Stood in the War’s Path

Benjamin Wright, often called the father of American civil engineering, built the Monocacy Aqueduct between 1829 and 1833. Workers hauled big quartzite stone blocks from nearby Sugarloaf Mountain to build it.

Each of the seven arches spanned 54 feet, and the whole project cost $127,900 – a huge amount for the 1830s. Canal experts thought it was one of the best examples of canal building in America.

The First Try to Destroy It Failed Badly

Hill’s soldiers tried to wreck the aqueduct but quickly hit problems. They didn’t have enough black powder to blow up such a massive structure.

Their tools couldn’t even scratch the thick stone. The men damaged Lock 27 and broke several canal banks instead.

One officer wrote about the aqueduct’s “very solid and massive” build as they gave up their first try. The stone was too strong for their limited tools.

A Lockkeeper Risked Everything to Save His Aqueduct

Walter heard about the Confederate plans to destroy the aqueduct and rushed to step in. He faced General Hill directly, arguing strongly for why the structure should stay standing.

Walter suggested that simply draining the canal would stop boat traffic just as well. People who watched worried Walter might get arrested for his bold approach.

His love for the canal structure outweighed his Southern support in that key moment.

His Smart Thinking Saved an Irreplaceable Structure

Hill agreed with Walter’s point about draining the canal. The Confederate forces then focused on breaking the more easily fixed Lock 27 instead of the massive stone aqueduct.

Walter cleverly shifted destruction from the irreplaceable marvel to structures workers could rebuild.

On September 5, Hill’s men kept destroying locks and burning canal boats, but left the aqueduct alone.

Lee Sent New Orders to Finish the Job

General John G. Walker got new orders from Lee on September 9.

The instructions told Walker to “completely destroy the aqueduct” at all costs. Walker came with proper tools and gunpowder to finish what Hill couldn’t do.

His engineering team started drilling to place explosives within the stone structure. They seemed set on bringing down the massive stone arches once and for all.

The Stone Proved Too Hard to Break

Walker’s men worked for hours trying to drill holes for their explosives. The stone proved too hard and their drills quickly became dull and useless.

One frustrated officer called the aqueduct “basically a solid mass of granite” in his report. The engineers finally quit, beaten by the amazing construction quality of the 30-year-old structure.

They couldn’t place a single explosive charge properly.

Union Artillery Made the Confederates Run Away

General Darius Couch’s Union forces showed up near the aqueduct on September 10 with artillery. They surprised the Confederate engineers still struggling with their destruction work.

Walker had to stop the operation and retreat toward Point of Rocks.

Federal artillery now controlled both the aqueduct and the paths to Cheek’s Ford, making further destruction attempts impossible as the campaign moved toward Antietam.

The Canal Company Fired Walter for “Helping the Enemy”

The C&O Canal Company quickly fired Walter for “working with the enemy” once they learned about his talks with Confederate officers.

Company officials saw his conversations with Hill’s forces as betraying Union interests. Walter faced losing both his job and his home after 23 years of loyal service to the canal.

His neighbors, however, had seen what really happened during those tense days.

Neighbors Rallied Behind the Clever Lockkeeper

Local residents created a petition demanding Walter’s reinstatement by the Canal Company. They testified that Walter had actually pleaded with Confederate officers not to destroy the canal structures.

The community argued that Walter’s quick thinking had saved the company thousands of dollars in reconstruction costs.

Canal officials eventually reinstated Walter, recognizing that his actions had protected the most valuable piece of infrastructure on the entire waterway.

Visiting C & O Canal National Historical Park, Maryland

The Monocacy Aqueduct at Mile 42.2 on the C&O Canal towpath tells the story of lockkeeper Thomas Walter’s tough choice during the Civil War.

You can park at Mouth of Monocacy Road in Dickerson and walk across the white and pink sandstone aqueduct built in the 1830s.

Check out nearby Lock 27 where Walter worked and see the restored lockhouse and old warehouse ruins. The park is free to visit.

This article was created with AI assistance and human editing.

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