PORTLAND, Maine — New England is in the midst of a major call-up of soldiers that eventually will lead to the deployment of roughly half of the National Guard personnel from Maine, Vermont and New Hampshire over the course of the coming year.

Hundreds of soldiers are mobilizing as part of the Vermont-based 86th Infantry Brigade Combat Team, which will go to Afghanistan early in the new year.

The unit’s latest send-off is for 150 soldiers from the Maine National Guard’s Bravo Company, 3-172nd Mountain Infantry Battalion, which is based in Brewer. The deployment ceremony is at 7 p.m. today at the Collins Center for the Arts in Orono and will be attended by Gov. John Baldacci and Maj. Gen. John Libby, adjutant general of the Maine National Guard.

Another 350 soldiers from Vermont National Guard said goodbye to their families and departed Sunday.

The Vermont National Guard deployment was in the works long before President Barack Obama’s announcement last week that he was sending 30,000 U.S. reinforcements to Afghanistan to help turn the tide against the Taliban and train Afghan security forces to defend against the militants.

Capt. Paul Bosse, Bravo Company’s commander, said his soldiers understand that things could come to a head with buildup of troops in Afghanistan in the new year.

“It’s a pivotal time. It’s a decisive time in the war,” said Bosse, an Old Town native and resident of Auburn. “I’ve got a lot of educated guys who watch TV and read the news. They understand the big picture.”

Eventually, more than 3,000 soldiers from New England will train at Camp Atterbury in Indiana before heading to Afghanistan, where the soldiers will serve in the mountainous eastern part of the country.

It’ll be the first time soldiers from the New England states have deployed as a brigade-size element, Col. John Boyd, the brigade’s second in command, said from Vermont.

For Vermont, it’s the largest single National Guard deployment since World War II, and its 1,500 soldiers represent roughly half of that state’s National Guard personnel. Eventually, Maine and New Hampshire will have half of their troops deployed as additional units leave in coming months.

In New Hampshire, the 197th Fires Brigade, an artillery unit, deploys to the Middle East in late summer or early fall with 1,100 Granite State soldiers in the state’s largest single deployment since World War II, said Maj. Greg Heilshorn, New Hampshire spokesman.

In Maine, the 1136th Transportation Company deploys in early 2010 to Afghanistan as well, and the 133rd Engineer Combat Battalion returns to Iraq in March; all told, more than 800 Maine soldiers will be deployed, said Capt. Shanon Cotta, the Maine National Guard’s spokesman.

In Afghanistan, it’ll be a more austere environment for Bravo Company, whose soldiers spent their last deployment in Iraq at Tallil Air Base, where the soldiers had running water, Internet access and American Forces Network television. But Bosse said his soldiers are eager to do what they’re trained to do.

“They’re excited about the mission. They think they can make a difference in their small part of Afghanistan, wherever that may be,” Bosse said.

Despite the resurgence of the Taliban, particularly in southern Afghanistan, Boyd said there are good things happening in the country. He already served one tour in Afghanistan and he returned for a two-week reconnaissance trip in October. He said the consensus is that security is improving.

“There’s progress there. There’s change. I’m not making light of the fact that it’s dangerous there. It’s a war zone, but there are so many sea changes going on in that country that’s bringing them into their form of democracy — not ours — that I was encouraged,” he said.

The Maine Army National Guard since 2001 has sent more than 2,300 men and women to Iraq and Afghanistan. Nine have died.