There are myriad other survivor benefits, too, many determined by specific circumstances. Joyce Wessel Raezer, chief operating officer of the National Military Family Association, said that a hypothetical widow of an Army corporal based at Fort Drum, in upstate New York, with three years of service and two young children would likely receive payments totaling $5,335 a month for the first year. In addition, a spouse would get free medical care for three years  the children into adulthood  and all would receive education assistance.

Through private companies, the Department of Veterans Affairs provides insurance beneficiaries the service of a professional financial planner for a year, but a spokesman said that only one in 10 families uses it.

Bill Saunders, director of client services for the Armed Forces Services Corporation, a private firm based in Arlington, Va., that offers military families advice on such issues, said that survivors are often overwhelmed by grief when they learn of the availability of financial advice, and that the military would do well to remind them after a few months.

“The money all shows up in their accounts within days or weeks, where there might have been $500 in there  ever,” Mr. Saunders said, referring to the lump sum of $500,000. “Many of these surviving spouses are young, which means they’ve never done any kind of money management or investing. So it’s completely foreign to them. It’s like saying, ‘Hey, would you like me to teach you Russian tomorrow? Come down to my office.’ And they don’t show.”

Ms. Avery, the widow who bought furniture and a purse  but not the BMW she coveted  credited her financial adviser with pushing long-term investment, but said she knows some widows who are now destitute.

“I do know that there have been widows who used all the money by paying cash for a house and paying cash for a car,” she said. “If they pay cash for a McMansion, they may not think about all the incidentals like heat and water and phone and cable and taxes and furniture.”

Image Debra vonRonn said she would have liked more attention from the military after her son, Sgt. Kenneth G. vonRonn, was killed. Credit... Joyce Dopkeen/The New York Times

One widowed acquaintance, whom Ms. Avery declined to identify to protect her privacy, ended up applying to the Army for an emergency relief loan after blowing through the $500,000. “You have to have nothing  like the electricity has to be getting turned off” to qualify for such a loan, Ms. Avery said. “In grief, you’re in such a state of shock that you don’t take into account that you won’t have your husband’s salary in six months.”