At the end of his junior year at Tufts University, Scott P. Brown did not take a typical summer job like many of his classmates. Instead, he spent two months in Army basic training at Fort Dix, N.J., after joining the Massachusetts National Guard.

Three decades later, Brown is a lieutenant colonel in the Guard, a state senator from Wrentham, and the Republican nominee in the Jan. 19 special election for US Senate.

Brown’s years as a citizen-soldier inform many aspects of his personal and political ethic: the value of discipline and physical fitness, his beliefs about national security, war, and peace, and his priorities in the Legislature.

Now, as a candidate for the Senate seat long held by the late Edward M. Kennedy, Brown often emphasizes his military background. His volunteers are called the Brown Brigade. After winning the GOP nomination on Dec. 8, he kicked off the general election campaign with a visit to the state Soldiers’ Home of Holyoke, criticizing Governor Deval L. Patrick’s budget cuts that forced closing of the outpatient clinic there a week earlier.

In the campaign, Brown takes a more hawkish line against terrorism than does the Democratic nominee, Attorney General Martha Coakley. Brown supports President Obama’s troop surge in Afghanistan and wants suspected terrorists tried in military tribunals, not civilian courts. Though he has never been deployed to a war zone, he said his service provides perspective on national security issues.

“The United States government has put a lot of money into my training,’’ Brown said in an interview. “I think about issues of war and peace almost all the time. I think about the men and women serving. I hear their stories, and I understand the terminology, and what’s at stake.’’

During six terms in the Legislature, three each in the House and Senate, Brown has a modest record of legislative initiatives, but he has carved out a niche as a leading advocate for veterans, colleagues on both sides of the aisle said.

Richard R. Tisei of Wakefield, the leader of the Republican minority in the state Senate, called Brown “the acknowledged expert on veterans’ issues.’’ State Senator John A. Hart Jr., Democrat of South Boston, said: “He does his homework, he’s comprehensive in his approach, and on veterans’ issues, he’s one of them and has done a very good job on their behalf.’’

As a legislator, he has served on the Veterans and Federal Affairs Committee, the Hidden Wounds of War Commission, and the Governor’s Task Force on Returning Veterans. He lists among his achievements his authorship of a 2007 law that created a check-off box on state income tax forms for veterans to indicate whether they served in Iraq or Afghanistan. The state uses the information to notify veterans of available services and benefits, including the “Welcome Home Bonus’’ that provides $1,000 for those returning from active duty in Afghanistan or Iraq.

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