Due to CapEx and defense spending, this order was now repeated in '11 and it accounted for $12.5 million of the $15.7 million revenue decline in Q4 of '11 versus '10. And so as you see while the defense business is very, very challenged, the defense business was also very, very profitable for us and this is reflected in our financials.
The Deliver and Service segment posted higher revenue for the quarter, despite encountering a variety of manufacturing issues during the launch of the Reach van and an unrelated delay in the shipping of some current step in units. Revenue for the quarter was up, still nearly 7% to $41.9 million due to higher aftermarket part sales primarily of the keyless remote product.
During the first half of 2011, we talked about steps we had taken to reduce our cost structure. As demand in some of our business segments had weakened. These steps were reflected in a lower operating expense for the fourth quarter, which was down $1.3 million from the fourth quarter 2010. We will continue to watch cost closely in all areas of our businesses and remain dedicated to aligning our cost base with our expected revenue stream.
Do we expect to reduce our cost base in 2012 versus 2011, the answer is yes. As this is an area under control and we have some very disciplined plans in place and we look forward to executing those plans.We ended the fourth quarter with net income of $0.02 per diluted share compared to $0.10 per diluted share in '10. Although, no one at Spartan was satisfied with our fourth quarter results, I am pleased with the progress we made during the challenging year, the execution of several strategic initiatives. And as I mentioned earlier, we're excited about the first half of 2012.