SHAQOULI, Iraq — To defend a few miles of unremarkable road in northern Iraq, flanked by farmland, the occasional factory and flyspeck hamlets and villages, the Islamic State militants seemed to spare no effort.
They loaded a Volkswagen with explosives and secreted remote-detonated bombs into the road’s median strip. They burned tires and dug large tunnels in houses, to obscure their positions. They placed crude mortar launchers on the road’s shoulder, pointed in the direction of any approaching force.
The arsenal ultimately failed to protect the militants as thousands of Kurdish soldiers known as peshmerga swept down the road Monday as part of a broader offensive to drive the militants out of Mosul. But it seemed to slow down the action Tuesday, tying up a large contingent of Iraqi soldiers for the better part of the day as they tried to clear the road and surrounding villages of booby traps, a few wearying feet at a time.
There were still 12 grueling miles left to travel before reaching the city’s outskirts.
The struggle for Mosul — which involves U.S. air power and an array of Iraqi ground forces — is the largest and most complex so far in the battle against Islamic State militants, who have been digging in for a fight. Residents who have recently fled the area and Iraqi officials with contacts inside the city say the Islamic State has been erecting concrete barricades and filling trenches with oil that can be set on fire to slow advancing forces.
