When King George II
took away
George Washington's
Birthday

(Possibly not a good idea.)

How did this happen?

In 1750 Britain passed a law,

An Act for regulating the Commencement of the Year,
and for correcting the Calendar now in use.

The full text of the law is at
1750 CHAPTER 23 24 Geo 2  1 
After all the Whereas stuff, the first actual paragraph, in bold, is:

The old supputation 2  of the year not to be made use of after Dec. 1751. Year to commence for the future on 1 Jan.The days to be numbered as now until 2d Sept. 1752; and the day following to be accounted 14 Sept. omitting 11 days. Hilary and Michaelmas terms, and all courts to be held on the same nominal days. Courts held with fairs or marts excepted.


This one law made
two unrelated changes
that were
several months apart.

1. It moved the start of the new year from March 25th, the traditional date of the vernal equinox, to January 1st, and

2. Nine months later, it eliminated eleven days to fully align the calendars on both sides of the English Channel, or Manche.

As a result of this law, the following dates never existed in Britain or its colonies:

January 1, 1751 (Old Style) through March 24, 1751 (Old Style),
and
September 3, 1752 (Old Style) through September 13, 1752 (Old Style).

While that is true, it may be incomprehensible. Let me try to explain it a different way. Historians and other scholars have converted dates in the old Julian calendar to the current Gregorian calendar. These converted dates are called New Style. In Britain the following occurred:

The day afterwas
December 31, 1750 (Old Style) January 1, 1750 (Old Style)  3 
March 24, 1750 (Old Style) March 25, 1751 (Old Style)  3 
December 31, 1751 (Old Style) January 1, 1752 (Transitional)  4 
March 24, 1752 (Transitional) March 25, 1752 (Transitional)  4 
September 2, 1752 (Transitional) September 14, 1752 (New Style)  5 

Okay, that still may not help. Let's look at it yet another way:

The Calendar as
George Washington
Experienced It

1750, a 365-day Julian year, is in PINK.
1751, a 282-day transition year, is in GREEN.
1752, a 355-day proto-Gregorian year, is in YELLOW.
New Year's Days are shown in RED.
Washington's Birthday is shown in BLUE.

1749      January               February               March          1749
1749 Su Mo Tu We Th Fr Sa  Su Mo Tu We Th Fr Sa  Su Mo Tu We Th Fr Sa 1749
1749     1  2  3  4  5  6               1  2  3               1  2  3 1749
1749  7  8  9 10 11 12 13   4  5  6  7  8  9 10   4  5  6  7  8  9 10 1749
1749 14 15 16 17 18 19 20  
11
 12 13 14 15 16 17  11 12 13 14 15 16 17 1749
1749 21 22 23 24 25 26 27  18 19 20 21 22 23 24  18 19 20 21 22 23 24 1749
1749 28 29 30 31           25 26 27 28           
25
 26 27 28 29 30 31 1750
1750        April                  May                   June         1750
1750 Su Mo Tu We Th Fr Sa  Su Mo Tu We Th Fr Sa  Su Mo Tu We Th Fr Sa 1750
1750  1  2  3  4  5  6  7         1  2  3  4  5                  1  2 1750
1750  8  9 10 11 12 13 14   6  7  8  9 10 11 12   3  4  5  6  7  8  9 1750
1750 15 16 17 18 19 20 21  13 14 15 16 17 18 19  10 11 12 13 14 15 16 1750
1750 22 23 24 25 26 27 28  20 21 22 23 24 25 26  17 18 19 20 21 22 23 1750
1750 29 30                 27 28 29 30 31        24 25 26 27 28 29 30 1750
1750         July                 August              September       1750
1750 Su Mo Tu We Th Fr Sa  Su Mo Tu We Th Fr Sa  Su Mo Tu We Th Fr Sa 1750
1750  1  2  3  4  5  6  7            1  2  3  4                     1 1750
1750  8  9 10 11 12 13 14   5  6  7  8  9 10 11   2  3  4  5  6  7  8 1750
1750 15 16 17 18 19 20 21  12 13 14 15 16 17 18   9 10 11 12 13 14 15 1750
1750 22 23 24 25 26 27 28  19 20 21 22 23 24 25  16 17 18 19 20 21 22 1750
1750 29 30 31              26 27 28 29 30 31     23 24 25 26 27 28 29 1750
1750                                             30                   1750
1750       October               November              December       1750
1750 Su Mo Tu We Th Fr Sa  Su Mo Tu We Th Fr Sa  Su Mo Tu We Th Fr Sa 1750
1750     1  2  3  4  5  6               1  2  3                     1 1750
1750  7  8  9 10 11 12 13   4  5  6  7  8  9 10   2  3  4  5  6  7  8 1750
1750 14 15 16 17 18 19 20  11 12 13 14 15 16 17   9 10 11 12 13 14 15 1750
1750 21 22 23 24 25 26 27  18 19 20 21 22 23 24  16 17 18 19 20 21 22 1750
1750 28 29 30 31           25 26 27 28 29 30     23 24 25 26 27 28 29 1750
1750                                             30 31                1750
1750       January               February               March         1750
1750 Su Mo Tu We Th Fr Sa  Su Mo Tu We Th Fr Sa  Su Mo Tu We Th Fr Sa 1750
1750        1  2  3  4  5                  1  2                  1  2 1750
1750  6  7  8  9 10 11 12   3  4  5  6  7  8  9   3  4  5  6  7  8  9 1750
1750 13 14 15 16 17 18 19  10 
11
 12 13 14 15 16  10 11 12 13 14 15 16 1750
1750 20 21 22 23 24 25 26  17 18 19 20 21 22 23  17 18 19 20 21 22 23 1750
1750 27 28 29 30 31        24 25 26 27 28        24
 25 
26 27 28 29 30 1751
1751                                             31                   1751
1751        April                  May                   June         1751
1751 Su Mo Tu We Th Fr Sa  Su Mo Tu We Th Fr Sa  Su Mo Tu We Th Fr Sa 1751
1751     1  2  3  4  5  6            1  2  3  4                     1 1751
1751  7  8  9 10 11 12 13   5  6  7  8  9 10 11   2  3  4  5  6  7  8 1751
1751 14 15 16 17 18 19 20  12 13 14 15 16 17 18   9 10 11 12 13 14 15 1751
1751 21 22 23 24 25 26 27  19 20 21 22 23 24 25  16 17 18 19 20 21 22 1751
1751 28 29 30              26 27 28 29 30 31     23 24 25 26 27 28 29 1751
1751                                             30                   1751
1751         July                 August              September       1751
1751 Su Mo Tu We Th Fr Sa  Su Mo Tu We Th Fr Sa  Su Mo Tu We Th Fr Sa 1751
1751     1  2  3  4  5  6               1  2  3   1  2  3  4  5  6  7 1751
1751  7  8  9 10 11 12 13   4  5  6  7  8  9 10   8  9 10 11 12 13 14 1751
1751 14 15 16 17 18 19 20  11 12 13 14 15 16 17  15 16 17 18 19 20 21 1751
1751 21 22 23 24 25 26 27  18 19 20 21 22 23 24  22 23 24 25 26 27 28 1751
1751 28 29 30 31           25 26 27 28 29 30 31  29 30                1751
1751       October               November              December       1751
1751 Su Mo Tu We Th Fr Sa  Su Mo Tu We Th Fr Sa  Su Mo Tu We Th Fr Sa 1751
1751        1  2  3  4  5                  1  2   1  2  3  4  5  6  7 1751
1751  6  7  8  9 10 11 12   3  4  5  6  7  8  9   8  9 10 11 12 13 14 1751
1751 13 14 15 16 17 18 19  10 11 12 13 14 15 16  15 16 17 18 19 20 21 1751
1751 20 21 22 23 24 25 26  17 18 19 20 21 22 23  22 23 24 25 26 27 28 1751
1751 27 28 29 30 31        24 25 26 27 28 29 30  29 30 31             1751
1752       January               February               March         1752
1752 Su Mo Tu We Th Fr Sa  Su Mo Tu We Th Fr Sa  Su Mo Tu We Th Fr Sa 1752
1752         
  1 
 2  3  4                     1   1  2  3  4  5  6  7 1752
1752  5  6  7  8  9 10 11   2  3  4  5  6  7  8   8  9 10 11 12 13 14 1752
1752 12 13 14 15 16 17 18   9 10 
11
 12 13 14 15  15 16 17 18 19 20 21 1752
1752 19 20 21 22 23 24 25  16 17 18 19 20 21 22  22 23 24 25 26 27 28 1752
1752 26 27 28 29 30 31     23 24 25 26 27 28 29  29 30 31             1752
1752        April                  May                   June         1752
1752 Su Mo Tu We Th Fr Sa  Su Mo Tu We Th Fr Sa  Su Mo Tu We Th Fr Sa 1752
1752           1  2  3  4                  1  2      1  2  3  4  5  6 1752
1752  5  6  7  8  9 10 11   3  4  5  6  7  8  9   7  8  9 10 11 12 13 1752
1752 12 13 14 15 16 17 18  10 11 12 13 14 15 16  14 15 16 17 18 19 20 1752
1752 19 20 21 22 23 24 25  17 18 19 20 21 22 23  21 22 23 24 25 26 27 1752
1752 26 27 28 29 30        24 25 26 27 28 29 30  28 29 30             1752
1752                       31                                         1752
1752         July                 August              September       1752
1752 Su Mo Tu We Th Fr Sa  Su Mo Tu We Th Fr Sa  Su Mo Tu We Th Fr Sa 1752
1752           1  2  3  4                     1         1  2 
  These 
 1752
1752  5  6  7  8  9 10 11   2  3  4  5  6  7  8 
 Days Did Not Exist  
 1752
1752 12 13 14 15 16 17 18   9 10 11 12 13 14 15 
 in Britain 
 14 15 16 1752
1752 19 20 21 22 23 24 25  16 17 18 19 20 21 22  17 18 19 20 21 22 23 1752
1752 26 27 28 29 30 31     23 24 25 26 27 28 29  24 25 26 27 28 29 30 1752
1752                       30 31                                      1752
1752       October               November              December       1752
1752 Su Mo Tu We Th Fr Sa  Su Mo Tu We Th Fr Sa  Su Mo Tu We Th Fr Sa 1752
1752  1  2  3  4  5  6  7            1  2  3  4                  1  2 1752
1752  8  9 10 11 12 13 14   5  6  7  8  9 10 11   3  4  5  6  7  8  9 1752
1752 15 16 17 18 19 20 21  12 13 14 15 16 17 18  10 11 12 13 14 15 16 1752
1752 22 23 24 25 26 27 28  19 20 21 22 23 24 25  17 18 19 20 21 22 23 1752
1752 29 30 31              26 27 28 29 30        24 25 26 27 28 29 30 1752
1752                                             31                   1752
1753       January               February               March         1753
1753 Su Mo Tu We Th Fr Sa  Su Mo Tu We Th Fr Sa  Su Mo Tu We Th Fr Sa 1753
1753   
  1 
2 3 4 5 6 1 2 3 1 2 3 1753 1753 7 8 9 10 11 12 13 4 5 6 7 8 9 10 4 5 6 7 8 9 10 1753 1753 14 15 16 17 18 19 20 11 12 13 14 15 16 17 11 12 13 14 15 16 17 1753 1753 21 22 23 24 25 26 27 18 19 20 21
22
 23 24  18 19 20 21 22 23 24 1753
1753 28 29 30 31           25 26 27 28           25 26 27 28 29 30 31 1753
So let's look at the way this affected one particular theretofore loyal subject of the Crown, George Washington of Virginia:

(Actual dates in use at the time have a blue background.)
Event Old Style Transitional New Style
His birth February 11, 1731  6  n/a February 22, 1732
His 19th birthday February 11, 1750 n/a February 22, 1751
His 20th birthday n/a February 11, 1752 February 22, 1752
His 21st birthday n/a n/a February 22, 1753

QED: George Washington did not have a birthday in 1751.

Notes:
 1  I love the cute way George II is known as "Geo 2" in the official statutes.
 2  I'm going to start using the word "supputation" whenever I can.
 3  This was the same way it had been for centuries.
 4  This was the new way, to be repeated every year afterward.
 5  This was a one-time-only kind of a deal.
 6  The Washingtons' pastor, or other learned acquaintance, might have written the date of his birth as "February 11, 1731/2" in the manner of the times.