Building The Block House


Photo credit – Roy Engelbrecht

The Fort Pitt Block House was constructed in 1764 as a way to reinforce the defense of Fort Pitt. To completely understand the need for a structure like the Block House, a little background of Fort Pitt prior to 1764 is necessary.

The fort itself was one of the largest fortifications in North America, and it consisted mainly of earthen construction with the majority of its ramparts and walls made up of dirt with sod bricks laid over them. This type of construction could withstand cannon attacks. The fort was completed by the end of 1761, its new “dirt” walls standing in place. The only thing that could potentially cause severe damage to the fort was flooding, a factor that the British had certainly considered prior to the building of Fort Pitt. It was ultimately decided to move forward with the fort’s construction with the hope that no major floods would occur in the near future.

Unfortunately for Fort Pitt, major flooding occurred almost immediately. On January 9, 1762, the three rivers surrounding the fort – the Allegheny, the Monongahela, and the Ohio – flooded, causing severe damage to the Fort. According to the fort’s commander, Colonel Henry Bouquet,

The 9th the Rivers run 10 Feet over the Banks, which had not happened at any flood since this Place is built…. The Water came upon us thro’ the Drains, Gate, and Sally Ports, and boiled in large Springs out of the ground in Several Parts of the Fort….. The 11th we could discover Part of our Disasters. All the Sod Work done last year, and great Part of the Year before tumbled down upon the Piquets, and a good deal of Earth washed away. (Bouquet Papers, January 12, 1762, Bouquet to J. Amherst).

Over a year later on March 9, 1763, another major flood hit the fort, rising twenty-two inches higher than the year before but causing less damage. The floods of 1762 and 1763 would prove to be the worst floods that Fort Pitt would ever see, and their heights would not be surpassed until the St. Patrick’s Day Flood of 1936 (Charles Stotz, Outposts of the War for Empire, 136-137).

Colonel Henry Bouquet

Colonel Henry Bouquet

Amidst this flooding was another threat to the fort: Native American Indian attacks. By the spring of 1763 Native American Indians throughout the Ohio River Valley region were upset with their treatment by the British. Throughout the French and Indian War (1756-1763), the British had promised to leave the Ohio River Valley for the Indians. They also promised to more or less abandon their fortifications in the Ohio Territories upon defeating the French. By 1760 the French had ceased to be a major threat to Pittsburgh and the fort; however, the Indians noticed the continuation of the building and garrisoning of Fort Pitt. The Ohio Indians also noticed the increase in British colonial settlement around the environs of Pittsburgh despite the promises of the British to prohibit such settlement from occurring. Finally, the Indians were increasingly denied trade items such as ammunitions, muskets, and rum by the British government.

All of these grievances led to Pontiac’s Rebellion (also known as Pontiac’s Conspiracy, Pontiac’s War, and Pontiac’s Uprising) in the spring of 1763. The uprising officially began in the west at Fort Detroit where Native Americans led by Ottawa Chief Pontiac besieged the British fort. Attacks began near Fort Pitt as early as May 28th with the fort under full siege by early June. Captain Simeon Ecuyer, placed in command of the fort, wrote the following to Colonel Bouquet shortly after the attacks began:

I think the uprising is general; I tremble for our posts. I think according to reports that I am surrounded by Indians. (Bouquet Papers, Ecuyer to Bouquet, May 30, 1763).

The Siege of Fort Pitt lasted into August of 1763, becoming the worst attack that the fort would ever experience. Colonel Bouquet set out with a small army of men to relieve Fort Pitt from attack. He encountered the Indians at Bushy Run, located to the east of the fort. The success of the British following the Battle of Bushy Run on August 5th-6th resulted in the lifting of the months-long siege (David Dixon, “Never Come to Peace Again”: The Pontiac Indian Uprising, 1763 to 1765, 193-194).

Following the floods and the siege, Fort Pitt lay in a vulnerable state. Repairs were made throughout 1762 and 1763 in attempts to strengthen its walls, but with very little aid coming from the British military, the fort continued to deteriorate. On December 27, 1763, Colonel Bouquet wrote to his commanding officer, General Gage, describing repairs and changes being made to the fort. Among the repairs and changes was the construction of three redoubts or block houses.

Three sides of this Fort which are not reveted [in brick] having been rendered almost defenceless by Two successive Floods in 1762, and 1763, I have caused Three Redoubts to be built on the glacis, to cover them. Two are compleated [sic], and the Third going on, as fast as the Weather will permit. (Bouquet Papers, Bouquet to Gage, December 27, 1763).

Photo credit – Roy Engelbrecht

One of these three redoubts was the building we know today as the Fort Pitt Block House. Unfortunately it is not known whether the Block House was one of the two built by December 1763 or if it was the third redoubt built at a later date (most likely by January 1764). Between December 1763 and September 1764 there five redoubts constructed altogether to help with the defense of Fort Pitt. One of the five redoubts was built entirely of wood. There were two redoubts along the Allegheny River side of Fort Pitt and two redoubts along the Monongahela River side. The Block House was located in front of the fort directly between the Monongahela and Ohio Bastions, facing toward the Point (Bouquet Papers, W. Grant to Bouquet, May 15, 1764 and Reid to Bouquet, Sept. 4, 1764).

The Block House is a two-story structure consisting of bricks, stone, and wood in its construction. Both floors have a course of gun loopholes going around the building, providing a 360 degree view for the soldiers who were stationed in the Block House to keep watch over the fort. If an enemy tried to attack, the soldiers in the Block House and other redoubts provided a first line of defense for Fort Pitt, and they could fire their muskets through the gun loops at anyone trying to attack.

 2011 Condition Report

The following is an excellent physical description of the Block House taken from a condition report in 2011 commissioned to determine the need for preservation and restoration work on the structure.

The building is five sided but is not pentagon in shape. The front and two sides are at right angles to each other with the two back walls forming a triangle or point. The building is twenty-three feet wide and twenty-six feet deep overall. Each sidewall measures sixteen feet long with the back walls measuring fifteen feet respectively. The footprint of the building encompasses four hundred and eighty three square feet. Each of the walls is constructed in five vertical layers as follows:

The foundation walls are of natural and rough cut limestone that has been laid in what could be referred to as an irregular Ashlar pattern. Overall the walls are two feet thick and extend four feet above grade (ground level). The interior ground floor of the building is sixteen inches below grade making the full height of the foundation wall above the floor five feet, four inches. An archeological report done in 2003 in conjunction with the installation of the new concrete floor suggests that the level of the original wood floor was slightly less than one and one-half feet below the present exterior ground level.

Photo credit – Roy Engelbrecht

Photo credit – Roy Engelbrecht

There is a timber course directly above the stone foundation walls. This course consists of a “mud plate” of what is believed to be white oak. Each oak plate is two inches thick, twelve inches wide and extends the full length of each wall. Setting on top of each mud plate there is an oak timber that is ten inches thick and twelve inches wide. These timbers form “gun loops” and have tapered openings cut into them at regular intervals.

A three wythe brick wall sets on top of each timber course. The walls are one foot thick and extend to a height of eight feet, six inches. The thickness of the walls is reduced to two wythes of brick (eight inches thick) eighteen inches above the timber course. The resulting reduction visible on the interior of the building forms a ledger that supports the floor joists of the second story. The brick walls are topped by a second timber course of similar dimension to the one above the stone foundation. A second brick wall section sets on the top of the uppermost timber course. The section of wall is of two wythe construction and is eighteen inches high. Overall the exterior walls extend sixteen feet above grade.

The building is topped by a five-sided hip roof. The roof framing consists of oak rafters set at two-foot centers (intervals). Horizontal collar ties (oak) help support the rafters at mid-span. The roof decking consists of contemporary pine board skip sheathing to which wood shakes (shingles) have been applied (Mark D. Clark, The Fort Pitt Block House Conditions Survey & Preliminary Restoration Plan for March 2011, 5-6).