Ambler was British-American, a preacher, reformed drunkard, drill sergeant and occasional author who recollected in his writing after the war his meeting with William Scott.
Ambler was abandoned as a child in England by his father after the early death of his mother. He spent his early years with his grandmother in a almshouse. He worked as a coal minor while still a child and later, when he was old enough, he joined the English army. He was a good student of military tactics but later deserted and escaped to America where he married and lived in Maine.
Ambler spent his time moving from town to town between Maine and Massachusetts. At some point, Ambler stopped drinking and became a part-time minister and preached abstinence. In Biddeford, Maine, he began to write his own biography with the idea of using the proceeds from the sale of his book to educate himself.
While Ambler was peddling his book in Boston, the Civil War broke out. With his knowledge of war, Ambler became an enthusiastic supporter of the Northern cause and urged men to enlist into the Union army. He also became a free-lance drill-master in Massachusetts.
His friends in Maine heard of his recruiting successes in Boston and urged him to return to Maine and help begin enlisting men for the Sixth Maine regiment. He became a self-appointed drill-master for the troops and accompanied them to the battle field.
After arriving at Chain Bridge, Ambler and his Maine recruits were formed into part of General Smith's brigade. It was at Chain Bridge that Ambler appointed himself not only drill-master to the new soldiers, but also as assistant chaplain and military handy man. He preached regular sermons and became a spiritual adviser to General Scott's brigade. Scott no doubt listened to his sermons and according to Ambler, they met together in the tent where Scott was confined after his court-martial.
Scott was tearful and obviously emotionally spent from the ordeal. In his writing, Ambler remembered Scott admitting through tears ..."that if I must be shot, Oh God, thy will be done."
Ambler tried to console the frightened soldier but became distraught himself over Scott's pending execution. He had earlier preached a sermon concerning the pending fate of the unlucky Vermont volunteer to the men and recalled the gloom that settled over the crowd of soldiers gathered around him.
"We knew he was a good soldier and never would have slept on his post if he had not been exhausted from heavy marching and overwork."
When the day of Scott's execution came, orders were given for twelve muskets to be placed in position, six to be loaded with live ammunition and six with blanks. Twelve men were detailed for the execution squad. Each soldier would select a gun without knowing which guns contained the blanks and which were loaded with ammunition.
The men filed out, six in a line and Scott in the center. Ambler walked beside Scott as they marched out into the execution square. Scott wore a piece of white cloth over his jacket to assist the gunmen in aiming directly at his heart. As they marched, Ambler spoke rapidly to Scott and encouraged him to die with soldierly dignity and as a Christian. Scott walked with his head down and held a bible. He kept nervously turning one thumb over the other as he walked with Ambler at his side.
In Ambler's view, an American soldier such as Scott should die as an English soldier would.
"I had seen English soldiers kneel on their coffins and open their bosoms with their own hands until six bullets pierced them and fall headlong into their coffins. I was anxious that William should stand as firm."
The spot where Scott was to die was formed into an open triangle of about ten thousand men, its open point facing into Virginia. Scott faced the open point. Ambler stood next to him as the charges were read and continued to encourage him until he had to step aside as the twelve men got into position to fire. Scott looked towards Virginia, then at Ambler and finally lowered his head.
Ambler's recollection of what happened next may have been muddled with Janvier's poetic version but he told a good story.
A horseman came galloping into the square waving his sword in the air. He dashed into the crowd and handed a dispatch to an orderly who passed it to the officer in charge. The officer then read the full pardon given by Lincoln while the soldiers cheered wildly.
When Scott heard the pardon, he ran to Ambler and they embraced, crying as Ambler put it, like babies.
In a later edition of Ambler's book, printed in 1883, a testimonial appeared written by Isaac Frazier of the Sixth Maine Regiment and one of the men assigned to execute Scott. He wrote of the incident:
"Being a senior captain of the regiment, I became a member of that court-martial and was the only member who was not in favor of the enforcement of the army law, "To be shot dead"; and I think I am now the only survivor of that body. Knowing that fatigue, added to several days of physical suffering, had rendered the otherwise able soldier unfit for the tedious night-watch, I believed that some other punishment was advisable. The pitying love which our martyred Lincoln extended to the soldier is well portrayed in the book, and the young man's gratitude to him and his devotion to his country was attested at Warwick Creek with the rendering of his young life."