NU Online News Service, Sept. 12, 5:45 p.m. — Marsh & McLennan Companies Inc., New York, and Aon Corp., Chicago, marked Sept. 11 with quiet tributes to hundreds of colleagues lost in the Sept. 11, 2001, terrorist attacks on four passenger jets, the Pentagon and the World Trade Center in New York.

Many other insurers and insurance brokerage firms also suffered casualties, but the attacks were especially devastating for Marsh and Aon. The attacks killed 295 Marsh employees and 175 Aon employees.

“One year ago today was the worst day in our company’s history,” Marsh Chairman Jeffrey Greenberg said in a statement. “We are open for business on this dreadful anniversary, but as you know it is certainly not business as usual.”

Marsh brought in counselors for employees who decided to work, and it put television sets in place for employees who wanted to watch the local and national commemorations.

Greenberg said Marsh will erect a granite, bronze and glass memorial engraved with the signature of each of the 295 employees lost in the plaza next to the company’s headquarters. Construction is scheduled to begin next year.

Aon closed its New York offices Sept. 11, but more than 200 employees participated in a commemorative service at the company’s headquarters in Chicago, according to Aon spokesman Al Orendorff. The service included readings from the Aon Book of Remembrance, a section of the company’s Web site that provides a tribute for each of the Aon employees who died.

Patrick Ryan, Aon’s chairman, acknowledged in his statement that the events of Sept. 11, 2001, are still difficult to understand.

But “let us remember together, today,” Ryan said, “that the humanity we share is far more powerful than the forces that attempt to tear us apart.”

He urged everyone within Aon to continue to offer support to one another, and especially to remember the families of the employees who were lost.

“They are our family,” Ryan said, “and families look out for their own.”