"Now Thank We All Our God" is one of the most widely sung hymns in Germany.  It was written by Martin Rinkart, who was a Lutheran pastor serving a church in Eilenburg, Germany, during the 30 Year's War (1618-1648).  Famine and disease wiped out over one third of the population.  In 1637, Rinkart personally conducted more than 4000 funerals, including that of his wife.  On top of that, the  Swedish general who layed siege to the city demanded a large tribute (ransom) that the impoverished population could not possibly pay.  Rinkart interceded to try and get the payment reduced.  When the Swedish commander would not consider the pastor's request, Rinkart led his parishioners in prayer and hymn singing.  This demonstration of spiritual faithfulness moved the Swedish commander so much that he eventually reduced the tribute payment. 

The tune "Nun Danket Alle Gott" was written by Johann Cruger in 1647, and became paired with the text of Rinkart's hymn.  J S Bach "recyled" the tune as the theme in several of his chorales.  The unique harmonization most commonly used today was added by Felix Mendelssohn in 1840, who used it as the chorale to his second symphony, known as "Hymn of Praise".  It has become Germany's national hymn of thanksgiving.  This dulcimer arrangement is fairly "chord intensive", since it reflects as closely as possible Mendelssohn's harmonization.  The harmony part is really just the bass line from the Mendelssohn chorale arrangement.

Wishing you all a joyous and blessed Thanksgiving!

--Tull

Here are the complete set of lyrics:

Now thank we all our God, with heart and hands and voices,
Who wondrous things has done, in Whom this world rejoices;
Who from our mothers’ arms has blessed us on our way
With countless gifts of love, and still is ours today.

O may this bounteous God through all our life be near us,
With ever joyful hearts and blessèd peace to cheer us;
And keep us in His grace, and guide us when perplexed;
And free us from all ills, in this world and the next!

All praise and thanks to God the Father now be given;
The Son and Him Who reigns with Them in highest Heaven;
The one eternal God, whom earth and Heaven adore;
For thus it was, is now, and shall be evermore.