History holds many unpleasant, if not horrible truths. The Holocaust, U.S. internment of Japanese citizens during World War II, widespread lynchings during the Jim Crow era and the forced relocation of Native Americans are just a few such truths; truths about which we would rather close our ears and eyes instead of absorbing the horror.

The history of slavery in the United States and in the American Colonies before independence was won has long been an institution about which too many of us have averted our attentions. We in the northern parts of the country for generations believed it only was our southern countrymen who owned slaves and fought to maintain the institution. The truth, as is so often the case, however, is much more complex.

During Colonial times and into the early 19th century, many wealthy residents of Connecticut and other northern states owned slaves. Seaports such as New London grew wealthy, in part, from direct slave trade or providing goods that supported slavery and brutal plantation life in the West Indies and elsewhere. New London and other parts of southeastern Connecticut were home to a high percentage of enslaved residents during colonial days.

New London is now a community that is reckoning with its past connections to the slave trade. On Sunday, the city honored enslaved Africans forced to travel to New London aboard the schooner Speedwell in 1761. With much ceremony, city leaders and local residents gathered at Amistad Pier to unveil a plaque designating the site as a UNESCO Slave Route Project Site of Memory. New London is one of 53 North American ports, and, along with Middletown, one of just two Connecticut cities to which enslaved Africans arrived directly.

The plaque, prominently located in a public area on a heavily traveled waterfront promenade, is evidence that New London wants its history — both that which is uplifting and unsavory — to be well known and better understood.

New London’s connection with the slave trade has never been completely hidden. Joshua Hempsted, who lived in the city during the 18th century and carefully chronicled Colonial life in a diary for 47 years, wrote about owning a slave. He also frequently mentioned other enslaved people owned by neighbors, family and friends. A logbook donated to the Connecticut State Library in 1920 recorded some slave voyages of New London ships. Seventeen years ago, a book titled “Complicity: How the North Promoted, Prolonged and Profited from Slavery” was written by then Hartford Courant reporter Anne Farrow.

In other ways, however, Connecticut’s connection to slavery has been obscured. When Norwich native-turned-traitor Benedict Arnold’s British troops stormed through New London during the American Revolution in September 1781, they burned much of the city, including its vast store of shipping records at the Custom House. Frances Manwaring Caulkins’ seminal history of New London, a book still widely used by scholars, never mentions the city’s participation in the slave trade. And for many years, American history lessons about slavery focused almost exclusively on the South, conveniently ignoring the long-standing northern participation in or support of the brutal institution.

We commend all those who worked to bring this important UNESCO designation to New London. It makes clear the city’s slave trade connections. Numerous officials, nonprofit groups and residents joined forces to make this public reckoning a reality.

While the city’s shameful connection to slavery and the slave trade is a historical truth we might rather stays hidden, only by understanding the full scope of history in all its darkness and light, can we begin to learn its valuable lessons. Go read the plaque and ponder the past. Come away with a deeper meaning of the truths of those who came before us.