The term “durable disorder,” which appears in “Mercenaries Know There’s Always Room for Specialists in the Market,” was coined by the improbably named Sean McFate, senior fellow at the Atlantic Council, professor of War and Strategy at Georgetown University and National Defense University, and a former contractor with DynCorp International.

The Meridian was an Anstruther fishing trawler lost in the North Sea east of Aberdeen in October 2006, while on contract as a repair guard vessel for Talisman Energy, a Canadian company.

Italicized line 28 in “Whose Deaths Were Recorded Officially as Casualties of ‘the Battle of May Island’” quotes Ovid’s Metamorphosis, translated by Anthony S. Kline. Line 41 closely follows one of its phrases, and 36 is from Dionysius the Areopagite’s The Divine Names and Mystical Theology, translated by J. Jones (Marquette University Press, 1980). The Royal Navy’s hugely expensive K-class submarines, designed in 1913, soon earned the nickname “Kalamity class” for their involvement in serious accidents. Admiral John (Jacky) Fisher, on hearing of their proposed design, responded: “The most fatal error imaginable would be to put steam engines in submarines.”

“He remembers a friend from his travels”: By the 7th century, druidism had gone largely underground to avoid persecution by Christian clerics. To ensure a continuity of belief, the Catholic church absorbed the stories of pagan deities into those of the saints and appropriated sacred sites for its sacraments.

Line 10 of “A visitation” arrived in a text from Ken Babstock.

The “white martyrdom” of “Hostilities were inevitable among the four peoples . . .” is one of three categories in the Cambrai Homily, an Irish text from the 7th or 8th century. White martyrdom was used by St. Jerome to describe the sacrifices of the desert hermits — the withdrawal from company, from all one loves, into a strict and often permanent ascetism. A red martyrdom, or blood martyrdom, was violent death resulting from religious persecution. Green (or blue) martyrdom represented self-denial and labour, and while not necessarily a withdrawal from common life, often involved a retreat to the natural world.

The Invertebrate Fauna of the Firth of Forth, Part 2, 1881, was compiled by George Leslie and William A. Herdman, and published from the Proceedings of the Royal Physical Society of Edinburgh, vol. 6.

Lines 7 and 8 of “‘Goodbye to Cockenzie Power Station, a Cathedral to Coal,’” revise phrases from Jean Moréas’ “The Symbolist Manifesto,” published in 1886.

The first line of the second stanza of “She Is Buried on the West Braes” is from the “First Merseburg Charm,” a pre-Christian incantation recorded in the 10th century. In the 18th century, at least 26 people accused of witchcraft were tortured and 18 killed in the village of Pittenweem. In March 2012, the village held a referendum on whether to erect Scotland’s first official memorial to victims of the trials. The vote being roughly 50/50, the community council decided against support for the memorial, citing fear of damage to the village’s reputation.