Crews battling the largest array of wildfires in Washington state history gained more ground against the flames on Tuesday, as property assessors reported the deadly conflagration had destroyed more than 170 homes and dozens of other structures. Containment of the sprawling cluster of blazes dubbed the Okanogan Complex, roaring through north-central Washington since mid-August, was estimated at 40 percent on Tuesday, up from 30 percent a day earlier, as firefighters capitalized on cooler, damper weather and lighter winds, authorities said.