Horse Guards≈五角大楼？

拉摩的侄儿

有意思：
https://archive.org/stream/waroffice032377mbp#page/n51/mode/2up/search/Horse+Guards

最早是指建立在比武场上近卫骑兵的营房，之后演变为了在那里办公的War Office（陆军部）的代称，最后随着The Secretary for War和Commander-in-Chief职责的分化、明确（最重要的是换办公室？），代指office of the Commander-in-Chief。
至于最后一个阶段具体什么时间实现的，还不能确定，不过，威灵顿在作为Commander-in-Chief时（1842-1852），他的办公室就是在Horse Guards。

拉摩的侄儿

The department had several London homes until it settled at Horse Guards in Whitehall during 1722, where it was to remain until 1858. The War Office was then relocated to Cumberland House, Pall Mall for the last half of the 19th century before finally being relocated to a purpose-built accommodation in what is now known as the Old War Office Building.

From the passing of the War Office Act 1870, as part of the Cardwell reforms, the C-in-C was made clearly subordinate to the Secretary of State, to serve as the latter's principal military adviser, and was made to move out of his traditional office above the arch at Horse Guards and into the War Office.
奇怪了 War office和Commander-in-Chief office一段时间里都是在HorseGuards

Abercomby

看来暂时只能具体问题具体分析，比如提到副官部，总军务长之类的，就是指陆军最高司令办公室