By tradition, regardless of the authorship question, scholars have assumed that the "three winters ... since first I saw you fresh" of Sonnet 104 refer to a three-year period including 1593 and 1594, when "William Shakespeare" dedicated his first publications (Venus and Adonis and Lucrece) to Henry Wriothesley, Third Earl of Southampton... 

The breakthrough discovery of THE MONUMENT, however, is that the "three winters" actually refer to Southampton's imprisonment from February 1601 to April 1603 -- specifically (1) February 8, 1601, the date of the Essex Rebellion; (2) February 8, 1602, the first anniversary of the failed palace coup; and (3) February 8, 1603, the second anniversary of the abortive attempt to overthrow the Elizabeth government under Robert Cecil's control. 

To me, fair friend, you never can be old,          
For as you were when first your eye I eyed,          
Such seems your beauty still: Three Winters cold       
Have from the forests shook three summers’ pride,       
Three beauteous springs to yellow Autumn turned,       
In process of the seasons have I seen, 
Three April perfumes in three hot Junes burned,
Since first I saw you fresh, which yet are green.          
Ah yet doth beauty, like a Dial hand          
Steal from his figure, and no pace perceived,        
So your sweet hew, which methinks still doth stand,    
Hath motion, and mine eye may be deceived.        
For fear of which, hear this, thou age unbred:  
Ere you were born was beauty’s summer dead.

THE MONUMENT changes the paradigm by identifying eighty consecutive verses (Sonnet 27 to Sonnet 106) as an intensely emotional diary recording events during Southampton's twenty-six months in prison.  This represents more than half the one hundred and fifty-four sonnets of the entire sequence. 

The great editor Hyder Edward Rollins predicted that such a dramatic shift of perception of Shakespeare's Sonnets would take place if only we could know the context of time and circumstance to which the verses refer. 

"The question WHEN the sonnets were written is in many respects the most important of all the unanswerable questions they pose.  If it could be answered definitely and finally, there might be some chance of establishing to general satisfaction the identity of the friend, the dark woman and the rival poet (supposing that all were real individuals), of deciding what contemporary sources Shakespeare did or did not use, and even of determining whether the order is the author’s or not. In the past and at the present, such a solution has been and remains an idle dream.”

                                                   A New Variorum Edition - 1944

THE MONUMENT answers the crucial question "when" by demonstrating that the story of the Sonnets revolves around the imprisonment Henry Wriothesley, Third Earl of Southampton from the Rebellion of 1601 until the death of Elizabeth and the accession of King James in 1603.

Once this altered view of the time frame comes into focus, we come face to face with Edward de Vere, Seventeenth Earl of Oxford, participating as a judge in the Treason Trial of February 19, 1601 and then doing everything possible to save his beloved Fair Youth from execution and gain his freedom.  This is the real story of the Sonnets and why Oxford agreed to sacrifice his identity as "Shakespeare," the poet who had publicly declared his commitment to Southampton ("The love I dedicate to your Lordship is without end") and now promised him: 

                         Your name from hence immortal life shall have,
                         Though I (once gone) to all the world must die.
                                                                           Sonnet 81

THREE WINTERS IN THE TOWER OF LONDON

  WINTER I:  February 8, 1601               
  SONNET 27: Rebellion & Imprisonment         

  Save that my soul's imaginary sight
  Presents thy shadow to my sightless view,
  Which like a jewel (hung in ghastly night)

                                      Makes black night beauteous and her old face new.          

WINTER II:  February 8, 1602      
SONNET 97: First Anniversary of Rebellion & Imprisonment

How like a Winter hath my absence been
From thee, the pleasure of the fleeting year!

WINTER III:  February 8, 1603
SONNET 104: Second Anniversary of the Rebellion                                            

Three Winters cold...                     
Since first I saw you fresh...

The eighty-sonnet prison sequence (27-106) contains two more verses:

SONNET 105:  March 24, 1603  
Death of  Queen Elizabeth I of England.

Let not my love be called Idolatry...

SONNET 106:  April 9, 1603       
Southampton's last night in the Tower.

When in the Chronicle of wasted time...

Southampton is liberated after having been "supposed as forfeit to a confined doom" in prison:

SONNET 107: April 10, 1603    

Southampton walks out of the Tower.

  
Not mine own fears, nor the prophetic soul
Of the wide world dreaming on things to come
Can yet the lease of my true love control,
Supposed as forfeit to a confined doom...