From The Missouri Muse, https://mostateparks.com/sites/mostateparks/files/Winter 2014_1.pdf
I recently discovered a reference to wooden mortars, built on site and used in the siege of Vicksburg (and later other places as well). The Missouri Muse attributes them to Chief Engineer Lt. Peter C. Hains of the 13th U.S. Army Corps of Engineers. However, in The War of the Rebellion: Official Records of the Union and Confederate Armies (Vol XV 1886. Vol 15 Chapter 27) they are attributed to the Irish engineer Stewart R. Tresilian, both in his report of the battle and in the report by Frederick E. Prime Captain of the Engineers and C.B. Comstock Captain of Engineers. (See quote below.) Tresilian himself, in his report, also mentions some cleverly constructed bridges made of cotton bales (of all things!), that he engineered. They apparently sustained the whole army over a river. Amazing.
I am trying to find more information about Stewart R. Tresilian and am having little luck. Does anyone have any rescources?
From Frederick E. Prime and C.B. Comstock's report, submitted November 29th, 1863: