Holy wells were often and some continue to be the focus of large gatherings of pilgrims, especially on special days of devotion such as the saints feast day/pattern day. In the 19th century and early 20th century some holy wells could attract hundreds even thousands of pilgrims, large gatherings could provide politicians/political groups with a captive audience and occasionally political meetings and rallies were organised to coincide with pilgrimages.
In the aftermath of the 1916 rebellion a number of pilgrimages at holy wells coincided with political meetings and anti-conscription rallies. In August 1917 the Irish Times ( 7th Aug 1917) tells that the Meath Sinn Fein Clubs held a public meeting on the pattern day of St Ciaran’s Holy Well (on the 1st Sunday of August), Caranross, Kells. Co Meath. Its was said upward of 8000 people were present and following prayers at the oratory beside the holy well, the Sinn Fein meeting was held in a field close by. The meeting was addressed by Countess Markievicz and Seam Milroy and ‘a large number of priests were present on the platform’.

St Ciaran’s Holy Well Carnaross Image taken ask about Ireland website (http://www.askaboutireland.ie/reading-room/history-heritage/folklore-of-ireland/the-holy-wells-of-meath-f/keenahene-loughan/)
Paddy Healy in his book Knocklyon Past and Present noted that at St Colmcille’s holy well at Knocklyon, Co Dublin was also the scene of a political rally, with a special pilgrimage organised to beg the saint’s intercession to avert conscription in Ireland.

Anti Conscription Rally at Ballaghadreen Co Roscommon Image taken http://www.irishhistorian.com/Selections/September_2013_Selection.html

St Colmcille’s Holy Well Knocklyon
In August 1918 the Derry Journal (19th August 1918) recorded the arrests of a number of Sinn Féin member’s for speaking at holy wells.
Thomas Murphy the Secretary of the Bray Sinn Fein Club was arrested in connection to speeches allegedly delivered at St Patrick’s Holy Well, Ballina, Co Mayo. John Moylett President of the the North Mayo Sinn Fein and Patrick Melvin of Ballina were also arrested in connection with this event.

St Patrick’s Holy Well Ballina. The well has been landscaped in recent years so would not have looked like this at the time of the rally. Image taken from Google Street View ( https://www.google.ie/maps/@54.121087,-9.162681,3a,75y,66.71h,75.83t)/data=!3m6!1e1!3m4!1seNpn-Nibz9EjA_oxQ5TvIA!2e0!7i13312!8i6656
The same paper also noted that
A large number of police had been drafted into Ballina in anticipation of a meeting but political speeches were delivered at the Holy Well to which a procession, said to be a pilgrimage, took place.
This statement indicates Sinn Fein either instigated a pilgrimage to the well or took advantage of an already organised religious gathering, to continue with the planned meeting.
The same article also mentions that John Curran secretary of the Letterkenny Sinn Fein club was arrested due to the reading of the Sinn Fein Executive proclamation at a meeting held at Conwal Holy Well a few miles outside of Letterkenny. The well is dedicated to St Catherine and was an active pilgrim site at the time of the meeting.
This is a topic I will return to again it is very interesting see these places of prayer becoming places where political messages could be communicated to a large audience and the act of pilgrimage used to mask a political agenda. I am sure there are other examples of this type of activity from elsewhere in the country and from earlier times , so I will keep you all posted on what I find out.