In June, British Navy transports escorted by 3 sloops-of-war had landed 700-800 soldiers and marines at Majabagaduce, a peninsula near the mouth of the Penobscot River. From this location, which was then in Massachusetts territory, the British intended to protect their possessions in eastern Canada from American incursions, raid the colonists' coastal shipping, and launch forays against New England cities and towns farther south. In addition, British commanders hoped to establish a colony of American loyalists.
Upon learning of the British incursion, the Massachusetts General Court, then in session in Boston, authorized an expedition to destroy the Penobscot base. The General Court also petitioned the Continental Congress for assistance from three Continental Navy warships anchored in Boston harbor. Congress agreed, and Commodore Dudley Saltonstall, commander of the squadron, was picked to lead the naval portion of the expedition.
Armed vessels from the Massachusetts and New Hampshire state navies joined Saltonstall's force, as did 12 privateers cajoled into state service for the expedition. Overall, the amphibious task force boasted 19 armed ships mounting 344 guns and 24 transports. The latter vessels carried a landing force of approximately 1,200 men under Brig. Gen. Solomon Lovell. The bulk of these troops were Massachusetts militia, joined by 300 Continental Marines. Ultimately, the Penobscot expedition turned into the largest American naval expedition of the Revolutionary War.
Saltonstall's orders directed him to completely eliminate the British presence in the Penobscot. To do so, his superiors emphasized, he would have to "preserve the greatest harmony with the commander of the land forces, that the navy and army may cooperate and assist each other." It was guidance that the commodore would discount, to the detriment of the entire mission.
After delays in loading the transports - caused in part by reluctance among the privateer captains to partake in such an unremunerative operation - the task force sailed from Boston on 19 July. It first proceeded to the area of modern Boothbay to pick up reinforcements that never materialized.
On July 25, the American warships entered Penobscot Bay. By this time, British naval commanders had good intelligence of the American force's composition and destination, and were preparing to find and destroy it.
When the Saltonstall's expedition first arrived in Penobscot Bay, British forces had only partially completed a dirt fortification, named Fort George, on the heights of the Majabagaduce peninsula. However, the three Royal Navy sloops, each mounting 18 guns, remained anchored in the bay nearby. A small party of British troops also had established a minor fortification on Nautilus Island just to the south of Majabagaduce peninsula. Hence, British gunners on land and on board the warships were able to engage in a desultory 2-hour duel with the American expeditionary task force as it entered the bay, which inflicted little or no damage on either side.
Initially, things went well for the revolutionary forces.
On July 26, Marines and militiamen, under covering fire from the American warships, took Nautilus Island and captured several British cannon.
On July 28, an American landing force stormed ashore on the southwest end of the Majabagaduce peninsula after 2 privateers had shelled the heavily wooded area above the landing beach. The initial echelon landed in 3 divisions, with approximately 200 militiamen on the left and in the center and 200 Continental Marines on the right. The Marines faced stiff resistance from several companies of British troops atop a steep bluff overlooking their landing point. Nevertheless, they cleared the bluff in less than 20 minutes, suffering 30-35 killed and wounded in the assault. Ensconced ashore, the American troops moved their artillery to a position only 600 feet from Fort George.
At this point, the American force began to move more cautiously, taking time to first build its own fortifications. Militia and marines next launched a night attack, conceived by Saltonstall, to seize a part of the British breastworks closest to the bay where the Royal Navy frigates had taken shelter. This would, the commodore believed, cut Fort George's garrison off from communication with their naval support, allowing the Americans to finish off each force individually. The assault on the breastworks succeeded initially, but the British men-of-war eventually opened fire on the position, causing the American forces to retreat to their own fortifications.
The results of the night-time action reinforced Brig. Gen. ?? Lovell's reluctance to commit his mostly green troops to an attack on Fort George while they remained exposed to potentially heavy land- and sea-based cannon fire. He urged Commodore ?? Saltonstall to attack the sloops, which his fleet outgunned, and thus remove that threat. Once this had been accomplished, the fleets guns could be used to suppress artillery fire from the fort during a subsequent American ground attack. Saltonstall, however, insisted that this course of action was too risky, continuing the pattern of ultra-cautious behavior that he had exhibited since the start of the operation.
In the ensuing days, Lovell and his militia commanders - and even some of Saltonstall's subordinates - pleaded with the commodore to attack the British sloops, but to no avail. Reports that a British naval force had sailed from New York to relieve the Pensobscot defenders, and that Fort George was becoming stronger by the day, still could not persuade the timid commodore. The continuing impasse poisoned interservice relations between the land and sea forces, all the way down to the unit level.
Meanwhile, Lovell and his men had been sending messages back to Boston on board fast ships - something the Commodore Saltonstall saw no need to do. The latter's superiors on the Navy Board of the Eastern District eventually supported Lovell's position and ordered Saltonstall to attack the British sloops and complete the operation before the Royal Navy relief force could arrive in his area. Reluctantly, Saltonstall made plans to take some sort of action on 13 August. But by then it was too late.
On August 13, 2 American warships acting as pickets spotted a task force under the command of Sir George Collier approaching the bay. Collier's force consisted of 6 warships, including a 64-gun ship of the line and 4 frigates. Saltonstall's warships still outnumbered the British and carried more guns, but the armament on board the Royal Navy ships outranged that of the Americans and their gun crews were far superior to their American counterparts.
Nevertheless, Saltonstall still had the opportunity to engage the British, damage some of their ships, and perhaps allow part of his own force to escape. At first, that appeared to be what he might try to do, as the American forces formed a defensive crescent across the bay. However, as the British moved closer, Saltonstall and his captains concluded that they could not overcome the enemy force. The entire American fleet turned tail and fled up the Penobscot River. Most crews ran their ships aground and set them afire.
Lovell's men fared little better. At word of Collier's approach, they evacuated their positions and reembarked their transports. These vessels ultimately joined their warship counterparts on the banks of the Penobscot. What was left of the American expedition - soldiers and sailors - had to travel overland through the dense wilderness to make their way back to Boston. In all, the Americans lost 43 ships and approximately 500 men. Massachusetts, which incurred a heavy debt outfitting the expedition, also suffered a major financial blow.
The committee of inquiry looking into the Penobscot fiasco placed most of the blame on the "want of proper spirit and energy on the part of the commodore," and Saltonstall was subsequently discharged from the naval service. Fundamentally, the expedition's failure highlighted problems with ambiguous command arrangements during amphibious operations. It also underscored the difficulty of mounting a large, complex expeditionary operation with a cobbled-together, untrained, and mostly nonprofessional force. In addition, the palpable mistrust and lack of communications between the naval and ground commanders - and their respective subordinates - demonstrated the importance of building a sufficient level of confidence and mutual understanding between land and sea warriors before an amphibious operation commenced.