BOSTON — More than a decade before he became the country’s first president, George Washington was leading a critical campaign in the early days of the American Revolution. The Siege of Boston was his first campaign as commander-in-chief of the Continental Army and, in many ways, set the stage for his military and political successes — celebrated on Presidents Day.

Following the Battles of Lexington and Concord, militias had pinned down the British in Boston in April 1775. The Continental Congress, recognizing the need for a more organized military effort, selected Washington to lead the newly-formed army.

What was the Siege of Boston

On this day 250 years ago, Washington would have been nearing the end of an almost yearlong siege that bottled up as many as 11,000 British troops and hundreds more loyalists. The British were occupying Boston at the time, and the goal of the siege was to force them out.

A critical decision made by Washington was sending Henry Knox, a young book seller, to Fort Ticonderoga in New York to retrieve dozens of cannons. The cannons, transported hundreds of miles in the dead of winter, were eventually used to fire on British positions. That contributed to the decision by the British, facing dwindling supplies, to abandon the city by boat on March 17, 1776.

Historians argue the British abandoning their position, celebrated in Boston as Evacuation Day, rid the city of loyalists at a critical time, denied the British access to an important port and gave patriots a huge morale boost.

“The success of the Siege of Boston gave new life and momentum to the Revolution,” Chris Beagan, the site manager at Longfellow House in Cambridge, a National Historic Site that served as Washington’s headquarters during the American Revolution. “Had it failed, royal control of New England would have continued, and the Continental Army likely would have dissolved.”

How the siege shaped Washington

The siege was also a critical test for Washington. A surveyor and farmer, Washington had been out of the military for nearly 20 years after commanding troops for the British during the French and Indian War. His successful campaign ensured Washington remained the commander-in-chief for the remainder of the revolution.

Doug Bradburn, president of George Washington’s Mount Vernon, said Washington took the first steps to creating a geographically diverse army that included militiamen from Massachusetts to Virginia and, by the end of the war, a fighting force with significant Black and Native American representation. It was the most integrated military until President Harry S. Truman’s desegregated the armed forces in 1948, he said.

Washington, a slave owner most of life who depended on hundreds of slaves on his Mount Vernon estate, was initially opposed to admitting formerly enslaved and free Black soldiers into the army. But short of men, Washington came to realize “there are free Blacks who want to enlist and he needs them to keep the British from breaking out” during the siege, Bradburn said.

Ridding Boston of the British also turned Washington into one of the country’s most popular political figures.

“He comes to embody the cause in a time before you have a nation, before you have a Declaration of Independence, before you’re really sure what is the goal of this struggle,” Bradburn said. “He becomes the face of the revolutionary movement.”

Commanding the military more than eight years also prepared Washington for the presidency, Pulitzer Prize-winning military historian Rick Atkinson said. “Perhaps most important, it gave him a sense that Americans could and should be a single people, rather than denizens of thirteen different entities.”

Myths of Washington

His rise to prominence also led to plenty of myths about Washington, many which persist to this day.

One of the most popular is the cherry tree myth. It was invented by one of Washington’s first biographers, according to George Washington’s Mount Vernon, who created the story after his death. Supposedly, a 6-year-old Washington took an ax to a cherry tree and admitted as much when caught by his father, famously saying “I cannot tell a lie … I did cut it with my hatchet.”

The second one is the wooden teeth myth. It was rumored that Washington had wooden dentures and scholars, well into the 20th century, were quoted as saying his false teeth were made from wood. Not true. He never wore wooden dentures, instead using those with ivory, gold and even human teeth.

More than a statesman

During his lifetime, Washington had a myriad of pursuits. He was known as an innovative farmer, according to the George Washington’s Mount Vernon, and an advocate for Western expansion, buying up to 50,000 acres of land in several Mid-Atlantic states. After returning to Mount Vernon, he built a whiskey distillery that became one of the largest in the country.

His connection to slavery was complicated. He advocated for ending slavery, and his will called for freeing all the slaves he owned after the death of his wife, Martha Washington. But he didn’t own all the slaves at Mount Vernon so he could’t legally free all of them.

Celebrating Presidents Day

For fans of George Washington, Presidents Day is their Super Bowl. Originated to celebrate Washington’s birthday, which falls on Feb. 22, the holiday has become associated with good deals at the mall. Still, there are plenty of places celebrating all things Washington on this day.

There will be a wreath-laying ceremony at Washington’s tomb at Mount Vernon, and there will be a Continental Army encampment. There will be a parade honoring Washington in Alexandria, Virginia, and, in Laredo, Texas, a monthlong celebration features a carnival, pageants, an air show and jalapeno festival.

Of all the winter pollutants, road salt, which lowers the freezing point of water, is the most concerning because it is particularly harmful to freshwater organisms that haven’t evolved to tolerate salt water, experts say.

“The reason this is an environmental issue for aquatic ecosystems is that salt specifically, is toxic,” said Andrew Hrycyna, water quality program manager at the Mystic River Watershed Association.

Hrycyna said the Environmental Protection Agency sets threshold levels for exposure to chloride, a part of salt that dissolves in water. Over time, such exposure can stunt growth and reproduction in fish and aquatic insects, while sudden exposure can cause them to die instantly.

Data collected for over 20 years by the Mystic River Watershed Association show an upward trend in chloride levels in freshwater sites across the waterbodies. The group measures “specific conductance,” a measurement of the electrical conductivity of water which is directly proportional with salt content, and has documented rising levels not only in winter but year round, suggesting that groundwater itself is becoming saltier.

A 2016 study by the United States Geological Survey found similar increases in chloride concentrations across rural and urban parts of New England, reinforcing concerns that the use of road salt has long-term regional impacts.

In Alewife Brook, a tributary of the Mystic River, chloride concentrations spiked sharply during snowmelt and rain events, monitoring during winter storms has shown. In some cases, levels briefly exceeded acute toxicity thresholds for freshwater organisms. Alewife Brook is now officially listed as “impaired” by chloride on Massachusetts’ Integrated List of Waters.

“The big problem comes not from the fact the snow melts, it’s the sheer volume [of salt] we’re using,” Hrycyna said. “We know we have to put some salt down to keep people safe, but can you put less and keep people equally safe?”

In most neighborhoods, storm drains are directly connected to nearby bodies of water through an underground pipe network. Anything on the street — from sand and soot, to dog waste and plastic debris — can be swept into rivers during snowmelt.

“It’s still precipitation,” said Chris Mancini, executive director of Save The Harbor/Save The Bay. “It’s still landing on urban streets, and where it melts, it’s carrying whatever it’s captured into storm drains over land into the water.”

Some cities, like Cambridge, are experimenting with brine, salt dissolved in water and sprayed onto roads, which allows for precise application and reduced overall use.

But there are other pollutants.

That black, crusty layer visible on plowed snow contains accumulated car exhaust particles, microplastics, sand and bacteria from pet waste. In the Charles River, elevated bacteria levels have the potential to make people sick. Nutrient pollution — including phosphorus from fertilizers, detergents and even organic matter like fallen leaves — can lead to over-fertilizing the river.

“It’s essentially like dumping fertilizer into the river, and you just get way too much plant growth, and it can actually overwhelm the river’s ecosystem,” said Julie Wood, climate resilience director at Charles River Watershed Association.

Advocates say the solution lies in redesigning how cities handle runoff.

Mancini said Boston’s Deer Island treatment plant and stormwater tunnels help manage intense runoff, storing and gradually releasing water to avoid overwhelming the system.

Green stormwater infrastructure, first pioneered in Maryland in the 1990s, is another part of the solution. These systems, which can take the form of sunken gardens, tree pits or underground infiltration tanks, capture runoff before it reaches storm drains. Soil and plant roots filter pollutants while water slowly seeps into the ground.

“That’s what we’re always pushing for both rainfall runoff and the snow melt,” Wood said. “Just natural filtration before it reaches the river.

Wood said salt remains harder to filter because it dissolves easily and can damage plants used in green infrastructure systems. That makes reducing salt use at the source especially critical. Mancini suggested the use of environmental friendly salt as an alternative.

There is, however, one environmental benefit to heavy snowfall. Wood said slow, gradual snowmelt allows water to recharge groundwater supplies, something intense rainstorms often fail to accomplish.

Still, advocates say the sight of blackened snowbanks offer a powerful visual reminder.

“Snow is just revealing to our eyes the pollution that’s always there year-round,” Wood said. “That black stuff we see on the snow is not only there in the winter, it’s just only visible in the winter.

Aayushi Datta can be reached at aayushi.datta@globe.com.

A police officer discharged their firearm, and a suspect is in custody after an incident in Boston late Saturday night.

Boston police had limited information on what occurred but said no one was shot in the incident around 10:29 p.m. in the area of 57 Cushing Avenue.

The suspect was taken to a local hospital for a medical evaluation, police added.

Further details were not shared.