Mackay's Regiment was one of the earliest Scottish regiments, being raised in 1626 and serving in the latter stages of the Thirty Years War in Germany on the Protestant side in the Swedish army. The great Swedish king and soldier Gustavus Adolphus, an ardent admirer of Scottish soldiers, incorporated the Regiment along with three other Scottish regiments, into his celebrated Green Brigade. The regiment first saw service under the King of Denmark, being raised by Sir Donald Mackay - later Lord Reay - and suffering grievous losses defending Danish territory against the advance of the Catholic Imperialists. When Sweden entered the war on the Protestant side, the regiment enlisted with him and drove deep into Germany, benefiting from the revolutionary battle tactics introduced by Gustavus. They took part in Gustavus's great triumph at Breitenfeld, and also in the hard-won victory at Lutzen in which the Swedish king was killed. At the subsequent Swedish defeat of Nordlingen, the regiment lost so many men that it was reduced to company strength. At the end of the war, the remnants of the regiment were amalgamated into the Royal Scots. This absorbing book will interest all members of the Clan Mackay and anyone keen on Scotland's proud military history.