21. Abatis ( obstacles made of felled trees ) were placed in front of the earth walls.22. An advance guard from Curtis's brigade used axes to cut through the palisades and abatis . 23. They were further protected by ditches surrounding the works, abatis , and rifle trenches and breastworks. 24. A classic use of an abatis was at the Battle of Carillon during the Seven Years'War. 25. Feodor I of Russia had built the abatis on the line Livny-Kursk-Voronezh-Belgorod. 26. Though they were sprayed by grapeshot from American gunboats, the grenadiers forced their way into the abatis . 27. The insurgents camped in a village of Ignacew, with their positions reinforced by abatis and a rampart. 28. The use of cannon against the French works would have cleared paths through the abatis and breached the breastworks. 29. Ostrogs were often built in remote areas or within the fortification lines, such as the Great Abatis Line. 30. An important weakness of abatis , in contrast to barbed wire, is that it can be destroyed by fire.
