What is a detailed analysis of Walter Scott's poem "Soldier, Rest! Thy Warfare O’er" in terms of language, structure, imagery, themes, and symbols?

Language
Soldier, Rest! Thy Warfare O'er comes from the First Canto of Sir Walter Scott's poem The Lady of the Lake (which comprises six cantos). The Lady of the Lake tells the story of Ellen Douglas, who is desired by three men (Roderick Dhu, Malcolm Graeme, and James Fitz-James), the conflict between the lowland and highland Scottish clans, as well as the conflict between the king (James Fitz-James) and the Douglas clan. Roderick Dhu leads the Highland clans against James Fitz-James, the king of Scotland. Meanwhile, Ellen Douglas is the lady of the lake (Loch Katrine in the Scottish Highlands). 
The poem Soldier, Rest! Thy Warfare O'er is actually a song sung by Ellen to James Fitz-James while he recovers from his hunt. It uses language that evokes the historical conflict between highland Scottish clans and King James V ("war-steed champing"), where war-horses chew on their bits in their eagerness to participate in battle. The Scottish "trump" or Jew's Harp is mentioned here, as well as the "pibroch," Scottish bagpipes commonly used to summon the clans as well as to lament the death of noted individuals. The tone of the poem is soothing and encouraging. Warriors are told to retire from the din of battle and to calm their spirits with rest and slumber.
Structure
The rhyme scheme of the poem is basically ABAB (or alternate rhyme) with the last four lines of every stanza a variant or modification of the initial ABAB rhyme of the first four lines. Soldier, Rest! is a narrative poem. It is also basically written in trochaic tetrameter. Trochaic refers to the accented/unaccented poetic feet in each line, and tetrameter tells us that there are four feet per line.
Soldier,/ rest! thy/ warfare/ o’er,/   Sleep the/ sleep that/ knows not/ breaking;/Dream of/ battled/ fields no/ more,/   Days of/ danger,/ nights of/ waking./
In our/ isle’s en/chanted/ hall,   Hands un/seen thy/ couch are/ strewing,/Fairy/ strains of/ music/ fall,/   Every /sense in /slumber/ dewing./
Scott uses caesura (a rhythmical pause in a line of poetry) to emphasize the call to tranquil rest: the words "Soldier, rest!" "Huntsman, rest!" and "Sleep!" are repeated in Stanzas 1 and 3, punctuating pauses in several lines. He also uses enjambment to create a sense of the sustained tumult of battlefield conflict.

Trump nor pibroch summon here   Mustering clan or squadron tramping.Yet the lark’s shrill fife may come   At the daybreak from the fallow,

Imagery
There is fantastic visual and sound imagery in the poem. Scott definitely provides clear images of warfare in Stanza Two. We can hear the din of war-horses galloping, the shouts of clansmen, and the clanking of armor.
No rude sound shall reach thine ear,   Armour’s clang, or war-steed champing,Trump nor pibroch summon here   Mustering clan or squadron tramping.
Guards nor warders challenge here,Here’s no war-steed’s neigh and champing,Shouting clans or squadrons stamping.
In her song, Ellen bids her guest to rest from the tumult and chaos of war ("Sleep the sleep that knows not breaking; Dream of battled fields no more, Days of danger, nights of waking"). She reminds him that at dawn in the Highlands, there are no shrill bugles to "sound reveille" or to summon one to war.
Themes
The theme of the poem is rest or repose from battlefield conflict. In the poem, Ellen bids James Fitz-James to retire from battle and the hunt. Although James is on a stag-hunt in Canto One, Scott may also be implying that James Fitz-James (also James V, the king of Scotland) should cease his enmity against the Highland clans.
Symbols
In the poem, the bugle, pibroch, and trump are instruments that summon soldiers to battle. Certainly, these musical instruments are not used for leisure. They are a jarring contrast to the "fairy strains of music" that are produced by the natural surroundings of Lake Katrine. 
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