The Siege of Petersburg was one of the most significant military campaigns of the final year of the Civil War. From June 1864 to March 1865, Union troops continuously besieged and harassed the Confederate railroad hub city of Petersburg, Virginia and surrounding environs in hopes of depleting both the Confederate Army and its nearby capital city, Richmond, of supplies and munitions. During those grueling nine months, heavy artillery played a central role in the eventual success of the Union’s campaign, which forced the Confederate Army to abandon Petersburg in March of 1865 and move westward toward Appomattox, where Robert E. Lee surrendered about three weeks later.
One of the most storied heavy artillery units that participated was the First Connecticut Heavy Artillery. Dispatched to join the Siege in May 1864, the First Connecticut “Heavies” were tasked with manning a massive, 13-inch mortar that was pivotal in decimating Confederate defenses surrounding Petersburg. Alternately referred to as the “Petersburg Express” or the “Dictator,” the 17,000 pound mortar was so heavy that it was kept mounted to a railroad car in order to allow troops to reposition it. The “Petersburg Express” fired up to 19 cannonballs weighing 225 pounds each, expending nearly 20 pounds of gunpowder with each shot.
In the 1890s, decades after the Civil War’s conclusion, a Connecticut veterans group began lobbying for a monument commemorating the brave actions of the Connecticut heavy artillery units that were so instrumental to the Siege of Petersburg’s success. After locating what they believed to be the very same “Petersburg Express” cannon in Fort Monroe, Virginia and transporting it to Connecticut, the veterans group proceeded to raise over $6,000 (with $1,000 provided by the state) to mount the mortar on a granite pedestal on the grounds of the State Capitol in Hartford. The monument was formally dedicated amid a crowd of thousands on September 25, 1902, on the anniversary of the mustering out of the First Connecticut Heavy Artillery.

Further Reading
Austin Sullivan, “A Monument Memorializes the Fallen,” connecticuthistory.org
Dave Pelland, “1st. Conn. Heavy Artillery Monument, Hartford,” ctmonuments.org