Major hotel chains are engaging in an online turf war with the very travel sites that have helped drive their businesses. From a report: Marriott, Hilton and InterContinental are using extensive marketing campaigns to claw back business from Expedia, Priceline and other travel-booking sites, which steer customers to hotel properties but also take commissions of up to 30% for each reservation. The chains are starting to treat these sites less as valuable business partners and more as gatekeepers standing between them and their customers. Many large hotel brands are offering lower nightly rates and other perks to loyalty members who book directly through their sites instead of online travel agencies. [...] The new battle is the latest episode in a two-decade "frenemy"-style relationship between online travel agencies and the hotel industry. Sites such as Expedia and Priceline were crucial for hotels during down periods such as after 9/11, but they have gradually eaten into the share of overall bookings ever since. Also read: Why Bargain Travel Sites May No Longer Be Bargains.