Dublin or Amsterdam - Which is better to visit.

Ireland and the Low Countries have different histories and cultures. An apples/oranges comparison, I think. Don't discount Dublin's charms. With your military interests you could easily spend a half-day at the Collins Barracks, one of the national museums in the capital. http://en.wikipedia.org/wiki/Collins_Barracks_(Dublin)
A national military museum is under construction in the Netherlands, but somehow military issues do not seem to loom so large for tourism. As an international and imperial country in the past it has certainly been involved in considerable strife, especially with the UN in more recent decades.
Even Dutch publicans (well, some of them) acknowledge Belgium as the epicentre of beer-drinking. The naval museum in Rotterdam with a collection of river and canal boats nearby is worth a few hours. Belgium has more than its share of World War battle sites, although its most famous battlefield, Waterloo, from an earlier war, by reputation does not offer a great deal to see now. You can find guided tours on the Internet.

There are two aspects to Irish history which I think might interest you on a visit to Dublin - the Viking era and the period 1913-1923 which takes in seminal events in the history of the Irish state (The Lockout, The 1916 Risiing, the following rebellion, partition and the civil war).

There are some interesting Viking sites in Dublin but much of it has been destroyed by development over the Millenia - there is however Dublinia and Viking splash tours (which may be abit on the less intellectual side for you) and the National Archaeology Museum in Kildare St which has some great Viking/Battle of Clontarf stuff on but that may be here when you arrive.

. In terms of the current centennial decade which is now being commemorated there is Collins Barracks as mentioned, Kilmainham Gaol (which is probably the better site IMO), the post office in O'Connell St, walking tours of the 1916 Rising, a Lock Out exhibition at the National Library (beside the archaeology museum), the memorial garden at the top end of O'Connell St, and many other sites such as the Four Courts (although this is particularly in relation to the Civil War).

Ireland does have Guinness and some great small brew ales (although not all pubs stock the latter) and the party chaos of Temple Bar (which may be to your liking).

Thanks for the tips. I also believe Ireland especially Dublin is cheaper to get to from the U.S. than Amsterdam is.